Method of maintaining availability of requested network resources, method of data storage management, method of data storage management in a network, network of resource servers, network, resource management server, content management server, network of video servers, video server, software for controlling the distribution of network resources

ABSTRACT

The availability of requested network resources in a network of servers, each having associated network-servable resources of a specific kind is maintained. Resource data and resource-serving application software serve out the resource data and dynamically distribute capacity to serve out servable resources between the resource servers dependent on demand for the resources. The capability of the network as a whole to serve out a particular resource dependent upon the level of demand for the particular resource is thereby varied. The capacity to serve out servable resources is distributed between the resources without necessarily moving the resource data itself between the servers by distributing: resource-serving application software and/or installation software adapted to install resource-serving application software.

FIELD OF THE INVENTION

[0001] The invention relates to a method of maintaining availability ofrequested network resources, a method of data storage management, amethod of data storage management in a network, a network of resourceservers, network, a resource management server, a content managementserver, a network of video servers, a video server and software forcontrolling the distribution of network resources.

BACKGROUND ART

[0002] The invention arose from a consideration of Internet Web Serversand it is convenient to discuss it in that context, but the inventionhas wider applicability to other networks. Current web server systems,for example e-commerce systems, application servers or any other webaccessible system, intended as web-servers for connection to theInternet typically comprise a web-tier, an application tier and astorage tier, see for example FIG. 1. The web-tier is typically highlyreplicated and homogeneous having a large number of web servers whichhave data and applications highly distributed over them in a homogenousmanner: the servers all do the same thing. Each of these web-serverswill serve the same data for a given service provider (e.g. xSPInternet, application or storage) in order to spread the accessibilityof the data to thousands of users. The data content of each server inthe web tier is therefore identical across all of the servers. Thisresults in a massive utilisation of disc space, in which some of thedata content is not heavily accessed. This leads to a large amount ofoften redundant storage: a lot of data content and application may benot be being served out at all frequently.

[0003] Load balancing (directing a specific request for a specificresource to be served out to a specific chosen sever on the web tier)can be used to attempt to provide a better, faster, service to users ofthe World Wide Web. For example “IP Virtual Server” software exists forLinux. Current web-based load balancing techniques for balancing theload between web tier servers are rudimentary and in one known versionof load balancing involve a principal server, router, or directorserver, distributing requests for data to a series of identical datacontent servers sequentially in turn until a server capable of servicingthe request is found. What the director server is looking for is aserver with the processing power free to service the request for data.It does this by asking a series of servers in “Round-Robin” until itfinds one capable. An alternative load-balancing technique for web tierservers is to have the director server (or router) send an investigatorysignal to the web tier servers and assess which server had the quickestresponse time, and to direct the request to be serviced to the web tierdata content server which replied fastest. This technique of measuringresponse time is primarily a measure of the telecommunications links tothe web tier servers: the capacity of the telecoms links is the majorfactor in response time. Depending upon whether the data content webtier server has a dedicated IC (interface card) or not, the responsetime may be influenced slightly by how busy the CPU of the web tierserver is, but telecoms factors far outweigh this usually.

[0004] Application servers (i.e. servers in a network serving to thenetwork particular applications—often different applications ondifferent networked servers) have a problem of scalability if demand fora particular application rises. Clustering is one answer to problems ofproviding greater access to data and functionality, but it is expensiveto replicate data content and functionality, and it is difficult toexpand the capacity of a cluster of services horizontally by theaddition of more resources in real time whilst the system isoperational.

[0005] Clusters are not easily scaled horizontally by the addition ofmore network attached storage (NAS) at the web-tier level. NAS typicallydoes not scale well horizontally as it is attached via a networkinterface card (NIC) to the network and there is a limit on the numberof network connections allowed by the NIC. A NIC has a capacity tohandle a limited number of connections. Cards are typically rated at 10Mbits⁻¹/100 Mbits⁻¹/1000 Mbits⁻¹. Clusters typically require thepurchase of expensive, cluster certified disc arrays and fibre channel,to support shared data between clustered servers.

[0006] Clustered systems typically fall into either a ‘sharedeverything’ class: where fibre channel, storage and switches etc. areshared by the clustered machines, or a ‘shared nothing’ class: whereeach machine on the cluster has its own storage, fibre channel andswitches etc. It is difficult to configure the cluster. The ‘sharednothing’ arrangement is very expensive with high end disc arrays costingaround $300 k per TeraByte (TB), and also as each disc cluster willcontain similar data content at each server, or node, the expenditure onstorage, and other peripherals, rapidly escalates.

[0007] A further problem with current web tier servers is that it isdifficult and expensive to add extra data. For example, in the field ofInternet Video Serving (serving out video movies over the internet) avideo website may have, say, ten web tier servers each having a copy ofthe one hundred most popular video films on them. A director server, orrouter, receives a request for a specific video and directs it to achosen one of the ten servers either on the basis of “Round-Robin”, orby assessing telecoms response time. The chosen server serves out theselected video. However, let us imagine that a new video is to be addedto the available videos. The new video is loaded into the memories ofeach of the ten web tier servers and added to the available videosdeliverable in the directory of the director server. It will probably benecessary to delete a video from the available number of videos to makeroom in the memories of the web tier servers.

[0008] A lot of the memory of each web tier server is not actively usedin any given period of time: a lot of it is redundant most of the time,but is needed in case there is a request for a less frequently requestedvideo.

[0009] There are difficulties in horizontally scaling. Adding anotherweb tier server means updating the director server and copying the datacontent of the other web tier servers to the new web tier server, sothat they are the same.

[0010] If it is desired to increase the number of video titles availableat that website it is necessary to increase the memory capacity (e.g.disc capacity) of each of the web tier servers so that they canaccommodate more videos.

[0011] Currently collections of servers that deliver content, e.g.streaming of videos, to a user are unaware of their storage capacity,connection capacity and bandwidth usage. A central management tool,typically a management protocol such as simple network managementprotocol (SNMP), loaded on an overseer machine, can in known systemsassume a wide scale, low level monitoring responsibility that willtypically include tripping an alert on a monitoring station if a server,or other network element, fails or if network traffic exceeds athreshold value. An attendant problem with this arrangement is that atthe time that an alert is registered it may be too late for a networkadministrator (person) to introduce a replacement server, or otheradditional network element, prior to a catastrophic system failure.Also, there may not be a network administrator present at all times toreact to a warning message.

[0012] An example, the wide variations in demand for web-sites, forexample an increased demand for information, or live video feed duringmajor sporting events, has resulted in web-sites crashing as the systemsadministrator cannot establish the rate of change of requests quicklyenough in order to add resources quickly enough to cope with thefluctuations in demand. A known solution to this problem is to massivelyover provide for the availability of data to users: to have much moredata-serving capacity than is normally needed. This is expensive andinefficient as at times of low data demand it results in large amountsof storage devices lying idle. High end disc arrays typically cost $300k per Tera Byte (TB).

[0013] It is possible to provide clusters of servers in order toaccommodate fluctuations in demand for data. However, as mentioned,clusters typically require the purchase of expensive, cluster certifieddisc arrays and network infrastructure, typically fibre channel, tosupport shared data between network nodes. Additionally, clusters tendto be built in advance of demand and are not readily horizontallyscaleable, for example by the addition of network attached storage (NAS)or by the addition of direct attached storage (DAS) to servers.

[0014] Video serving over the internet is currently not very popularbecause it is so expensive to do, for the reasons discussed.

SUMMARY OF THE INVENTION

[0015] According to a first aspect the invention comprises a method ofsatisfying a demand on a network for a network resource, the methodcomprising providing the network with a demand director server, a firstresource server having a first resource thereon, and a second resourceserver having a second, different, resource thereon; and the methodfurther comprising having said director server be aware of whatresources are held on said first and second resource servers and uponreceipt of a request for one of said first and second resourcesselecting one of said first and second resource servers to serve outsaid requested resource and directing said request to said selected oneof said first and second resource servers, said demand server selectingan appropriate one of said first and second resource servers to receivesaid request using its knowledge of where the requested resource islocated.

[0016] Previously in world-wide web-based networks there has been nodifferentiation in resources provided on web-tier servers: the datacontent and applications deliverable have been homogenous betweenweb-tier resource servers. Furthermore, even in other,non-internet/world wide web environments, networked servers capable ofserving out the same kind of resource (e.g. videos) have all hadidentical content: not different content per server.

[0017] In the above invention the demand director is aware of wheredifferent resources are stored so as to be able to direct a request forresources to the appropriate server that actually has the requestedresource stored on it, but the demand director is not necessarily awareof the current demand/load on each resource server—but it might be.

[0018] According to another aspect the invention comprises a method ofsatisfying a demand on a network for a network resource, the methodcomprising providing the network with a demand director server, a firstresource server having a first resource thereon, and a second resourceserver having a second resource thereon; and the method furthercomprises having said director server be aware of unusedresource-serving capacity of said first resource server and of unusedresource-serving capacity of said second resource-server, and saiddirector server upon receipt of a request for a requested resource whichis present on both said first resource server and said second resourceserver selecting a selected one of said first and second resourceservers to be the resource server that serves said requested resource,said director server selecting said selected one of said resourceservers using a knowledge of whether or not said first and secondresource servers have unused resource-serving capacity capable ofserving said requested resource.

[0019] In this aspect of the invention the director server isusage-aware (usage of the server, as well as or instead oftelecommunications availability to the server), and the content, orresources, of the resource server may or may not be dissimilar.

[0020] According to a third aspect the invention comprises a method ofsharing the demand for resources between a plurality of networkedresource servers comprising providing dissimilar resource content on atleast some different resource servers, having a knowledge of whatresource is available for serving out from which of said networkedresources servers, having a knowledge of said resource servers' currentcapacity to satisfy a request for resources that they are capable ofserving, and allocating a request for a requested resource to a selectedresource server chosen with the knowledge that it has said requestedresource available for serving and that it has the capacity to serve outsaid requested resource satisfactorily.

[0021] This aspect of the invention combines the first and secondaspects.

[0022] The director unit may also comprise a resource server (e.g. itmay also serve out resources such as videos). The data may be rich mediafiles, which typically include real time (RT) video and/or audio filesand/or MPEG files, and/or Real Networks format video data or WindowsMedia format data or any other file based format.

[0023] Each resource server may store dissimilar data content thereupon.By dissimilar we mean either (i) that the data, or resources, accessibleby an external user is not directly mirrored and completely replicatedacross all of the resource servers units (whereas the operating system,etc. can be the same for all of the resource servers); or (ii) that thedata, or resources, accessible by an external user is very substantiallydifferent between at least some of the resource servers; or (iii) thatthe data, or resources, externally accessible by a user is whollydifferent, or nearly so, between at least some of the resource servers,or (iv) that there is a great deal of data content, or resource,difference between different resource servers some of which may or maynot have any shared, common, deliverable-to-the-user resource. At oneextreme each resource server could have entirely different, or nearlyso, resource content—but it is not intended to avoid this patent simplyby duplicating some content between some or all resource servers.

[0024] The director server may have a database therein which may detailwhich resource server has any given resource thereupon and may detailany one, or combination of the following for any given resource: accessfigures, statistics, metrics on utilisation, number of clients, orusers, currently accessing the data, time periods of frequent accessnumber of clients, or users, historically served.

[0025] The resource servers may have data storage units associatedtherewith. The data storage units will typically be disc arrays but mayinclude tape drives. The data storage units may be internal of theresource servers and/or they may be external of resource servers, forexample network attached storage (NAS).

[0026] The director server may be arranged to load balance data accessand/or the distribution of data across the server network, or across aserver farm. The concept of moving data, or resources, around thenetwork automatically to improve network performance is interesting andnovel.

[0027] A request may be serviced by whichever resource server isadjudged to be the most able to serve out said requested resource. Thisconcept of being aware of capability capacity to serve out, and makingdecisions relating to resource management and availability based uponsuch knowledge constitutes a separate invention.

[0028] A requested selected resource server may serve up a reply to arequest for resource in such a way that said reply appears to arequester who made said request to be coming from said demand director.The demand director server may be arranged to forward a packet of arequest to a chosen resource server The chosen resource server re-writesthe packed header. The resource server may have first and second networkinterface cards (NIC'S). The second NIC may be configured to enablecommunications with an external network. The demand director server mayhave an interface, which may be arranged to specify input/output portsfor an application and/or resource servers. The first NIC may beconfigured to enable intra-farm, or intra-network communication,typically with the demand director server. Having two subnets serves torestrict communications with outside users and movement of data withinthe farm or network to alter its availability to serve: thus one subnetmay exist for each function so as not to congest either subnet.

[0029] The resource server may be arranged to rewrite the packet headersof outgoing data such that they appear to be transmitted from the demanddirector server. This will typically involve writing a network addressof the director unit, usually a transmission control protocol/internetprotocol (TCP/IP) address, with the packet header.

[0030] The director may provide an ephemeral means to access the datae.g. via the use of a file systems symbolic link which is typically timelimited and is removed after the expiry of a pre-determined length oftime, usually after a client, or user, has already started accessingresources (e.g. content). The removal of the symbolic link does nottypically alter the client's consumption of the data but will usuallyprevent reaccess of the data without requesting a new session throughthe director.

[0031] The demand director server may be arranged to configure and/orstart and/or stop resources (or applications) upon the resource serversand/or add, and/or remove, at least one resource server from thenetwork, or farm, in response to variations in the number of requestsfor data. Alternatively, the director unit may be arranged to recommendto an administrator (e.g. a person) the addition/removal of at least oneresource server to/from the farm (or network) in response to variationsin the number of requests for resources. The demand director server maybe arranged to distribute data over the resource servers of thenetwork/web tier/farm.

[0032] A copied resource may be created by copying resource from a saidresource server onto another said resource

[0033] server, and having said demand director be aware that said copiedresource exists on said another resource server. The copying of saidcopied resource may increase the availability of said copied resourceavailable for serving out from said resource servers. Resource may bedeleted from a selected resource server, thereby freeing-up resourceserver capabilities for use to serve up a different resource. It is insome embodiments desirable to dynamically distribute servable resourcesbetween available resource servers dependent upon demand for saidresources, and to vary the capacity of said resource serverscollectively to serve out demand for a particular resource dependentupon the demand for said particular resource. The demand director servermay be capable of communicating with an additional resource server thatpreviously was not making its resources available for serving requestsreceived by said demand director server, and of arranging for saidadditional resource server to make its resources available for servingrequests received by said demand director server.

[0034] In some embodiments the invention provides horizontallyscaleable, distributed data storage arranged to be connected to anetwork, typically for use with audio or video data.

[0035] The concept of copying, or migrating, data dynamically to expandoverall network capacity to serve out a particular kind of resource canapply to the prior art arrangements where all web tier servers have thesame content/resources. It is still possible to add a server (with thesame content) to the network in response to demand. It is still possibleto increase the capacity of all servers together to serve out a specificresource that is in demand (e.g. a further copy of the most popularmovie could be added to each content server in response to demand,possibly at the expense of over-writing a copy of a less popular movie.It is not absolutely essential to use different, asymmetricallydistributed, resources/content to use the “migration/copying of content”invention.

[0036] There may be more than one demand director server. This increasesfault tolerance.

[0037] According to another aspect of the present invention there isprovided a demand director server comprising a processor and a datastorage device, the demand director server being arranged to manageasymmetric distribution of data across a plurality of data storagedevices and mediate requests for access to said data so as to loadbalance the requests for data received by each of the data storagedevices.

[0038] The demand director may copy data to different memory locationsitself, or it may initiate a data copying process that is actuallyperformed by another machine. The management of the data across theplurality of storage devices improves the efficiency of data storage.The load balancing of the requests for data improves the efficiency ofusage of the storage devices and aims to ensure a high degree ofreliability to the supply of the files to a user.

[0039] The processor may be arranged to facilitate the uploading of datafrom tape media, a DVD or audio CD to the storage devices.Alternatively, the processor may be arranged to facilitate thedownloading of data from a network, typically the Internet.

[0040] The processor may be arranged to update a data (or resource, orcontent) location database, for example whenever any one, or more, ofthe following occurs: the number of storage devices is increased ordecreased, data is copied to or deleted from a storage device, data isuploaded, or downloaded, to a storage device, an application, orresource, resident upon a data storage device is started up or shutdown.

[0041] The demand director server may be arranged to act as a Level 7switch. High level network switches are aware of the types of requestbeing made within a data packet and can deal with the contents of thepacket dependent upon the type of request. Level 7 switches aredescribed in the Open Systems Level model of network informationsystems.

[0042] According to another aspect of the present invention there isprovided a method of data storage management of data in a networkcomprising the steps of:

[0043] (i) monitoring the usage of a servable resource;

[0044] (ii) determining if the usage of said resource has increased ordecreased;

[0045] (iiia) introducing an additional resourcer server to the networkand/or starting up a resource-serving application on a resource serverif the usage has increased; and/or

[0046] (iiib) removing said resource from a resource server and/orshutting down a resource-serving application on a resource server if theusage has decreased.

[0047] In many embodiments, especially those with asymmetricallydistributed resources/content over the resource servers, the method willalso update a database containing details of which resource servers havewhich particular resources thereupon.

[0048] The method may include removing a resource server from thenetwork as part of step (iiib). The method may include copying aresource to the additional resource server as part of step (iiia). Theresource may be a data file, such as a video.

[0049] According to a fourth aspect the invention comprises a servernetwork comprising a demand director server, a first resource serverhaving a first resource on it, and a second resource server having asecond resource on it, different from said first resource, said directorserver being aware of where said first and second resources are located,and being capable of receiving a request for a selected one of saidfirst or second resource to be served out, and of directing said requestto whichever said resource server is determined to have said requestedresource.

[0050] The request may originate from outside of said network, and theresource may be served out of said network.

[0051] According to another aspect the invention comprises a servernetwork comprising a demand director server, a first resourcer serverhaving a first resource thereon, and a second resource server having asecond resource thereon; said demand director server being adapted to beaware of unused resource-serving capacity of said first resource serverand of said second resource server, and said director server beingcapable, upon receipt of a demand for a requested resource that ispresent on both said first and said second resource servers, ofselecting a selected one of said first or second resource servers toserve out said requested resource and causing said selected one of saidfirst or second resource servers to serve out said requested resource,said demand director being adapted to use a knowledge of said unusedresource-serving capacities for said selected resource of said first andsecond resource servers when selecting which resource server is to besaid selected resource server and serve out said selected resource.

[0052] According to another aspect the invention comprises a demanddirector server adapted for use with a plurality of resource-servingresource servers having resources distributed between them, said demanddirector being capable of monitoring and managing distribution ofresources across said resource servers, and of mediating requests forresources to be served out by said resource servers so as to direct arequest for resource-serving to a chosen resource server chosen by saiddemand director using a knowledge of which resource servers are capableof serving out the requested resource.

[0053] According to another aspect the invention comprises a method ofnetwork resource management comprising, in a network having a demanddirector and resource serving servers, the steps of:

[0054] (i) receiving at a demand director unit a request for a resourcefrom a requester;

[0055] (ii) determining the availability of resource serving serversthat are capable of serving said requested resource;

[0056] (iii) selecting a resource server that is capable of serving saidrequested resource and sending said request to the selected resourceserver;

[0057] (iv) establishing a connection between said requester and saidselected resource server;

[0058] (v) serving out said selected resource from said selectedresource server to said requester.

[0059] According to another aspect the invention comprises a method ofsatisfying a demand on an Internet network for a network resource, themethod comprising providing the network with a demand director server, afirst resource server having a first resource comprising one of a videofile and a data file thereon, and a second resource server having asecond, different, resource comprising one of a video file and a datafile thereon; and the method further comprising having said directorserver be aware of what resources are held on said first and secondresource servers and upon receipt of a request for one of said first andsecond resources selecting one of said first and second resource serversto serve out said requested resource and directing said request to saidselected one of said first and second resource servers, said demandserver selecting an appropriate one of said first and second resourceservers to receive said request using its knowledge of where therequested resource is located.

[0060] According to another aspect the invention comprises a method ofsatisfying a demand on an Internet network for a network resource, themethod comprising providing the network with a demand director server, afirst resource server having a first resource comprising one of a videofile and a data file thereon, and a second resource server having asecond resource comprising one of a video file and a data file thereon;and the method further comprising having said director server be awareof unused resource-serving capacity of said first resource server and ofunused resource-serving capacity of said second resource-server, andsaid director server upon receipt of a request for a requested resourcewhich is present on both said first resource server and said secondresource server selecting a selected one of said first and secondresource servers to be the resource server that serves said requestedresource, said director server selecting said selected one of saidresource servers using a knowledge of whether or not said first andsecond resource servers have unused resource-serving capacity capable ofserving said requested resource.

[0061] Whilst envisaged primarily for use with video files, theinvention can be used with other files (termed “data files” forconvenience).

[0062] In one embodiment the invention comprises a web tier of resourceserving servers comprising a plurality of resource servers at least someof which have different servable resource content, thereby enabling aspecific resource to be served out of one resource server but notanother.

[0063] In a further embodiment the invention may comprise a tier ofresource serving servers comprising a plurality of resource servers atleast some of which have different servable resource content of the samekind or class, thereby enabling a specific resource of a kind or classto be served out of one resource server but not another, both resourceservers having resources of said some kind or class.

[0064] There is usually also a demand director server which is aware ofwhich resources are servable out of which resource servers, and which iscapable of receiving a request for a particular resource and directingsaid request to a resource server capable of satisfying said request.

[0065] The demand director may be thought of as part of theresource-serving web tier, or as sitting above the resource serving webtier as a demand director server/router: i.e. a level 7 switch.

[0066] According to an aspect of the present invention there is provideda network having a plurality of networked resource servers havingdissimilar resource content, and a demand director, said demand directorbeing aware of what resources are potentially available on which of saidresource servers, and being capable of determining current capacity ofeach of said resource servers to serve out each of said resources thatthey are capable of serving out, said demand director being adapted toallocate a request for a specific resource to a resource server that itselects using its knowledge of what servers, and their capacity to serveout said requested resource.

[0067] According to an aspect of the prevent invention there is provideda demand director for use in a network of resource servers, said demanddirector having information associating specific resources available forserving out from specific resource servers, and being adapted toascertain the capability of said resource servers to serve out theirpotentially servable resources, and being adapted to allocate a demandfor a specific resource to a selected resource server using saidinformation and said capability.

[0068] According to another aspect of the present invention there isprovided a demand director for use in a network of resource servershaving resources that are potentially servable-out, said demand directorhaving the capability of ascertaining the capability of said resourceservers to serve out their potentially servable-out resources and ofusing a knowledge of the capability of said resource servers to serveout a specific resource in determining to which resource server arequest for said specific resource is directed.

[0069] According to an aspect of the present invention there is provideda network having a plurality of content servers capable of serving outcon tent of a particular kind stored upon them, and demand manager meansadapted to allocate a request for specific content to an appropriatecontent server for serving said request, said content servers havingdissimilar servable content of said particular kind stored uponthemselves and said demand manager means having mapping means mappingspecific content with specific content servers such that said demandmanager is adapted to receive a request for specific content and toallocate said request to an appropriate content server having saidspecific content upon it, using said mapping means.

[0070] According to an aspect of the present invention there is provideda network having a plurality of content servers capable of serving outcontent of a particular kind, and content server monitor means adaptedto monitor capacity of said content servers to serve out specificresources, said content server monitor being adapted to allocate arequest for requested specific content to a content server chosen bysaid content server monitor means using a knowledge of said capacity ofeach of said content servers to serve out said requested specificcontent.

[0071] According to an aspect of the present invention there is provideda metropolitan area video serving network comprising a plurality ofvideo servers having at least some different videos on at least some ofsaid video servers, and a demand director having a location mapcorrelating the address of which of said video servers has which of saidvideos available for serving, said demand director being adapted todirect demands for a specific video to an appropriate said video serverfor serving out said specific said video, using said location map toselect said appropriate video server.

[0072] According to an aspect of the present invention there is provideda metropolitan area video serving network comprising a plurality ofvideo servers having videos available for serving out, and a videoserver monitor and demand director adapted to establish the capacity ofsaid video servers to serve out additional videos, beyond their currentactivity, and to direct a request for a specific video to a video serverthat said video server monitor and demand director has established hassaid particular video and is capable of serving out said videosatisfactorily.

[0073] According to an aspect of the present invention there is provideda method of satisfying a demand on a network for a network resource, themethod comprising providing the network with a demand director server, afirst resource server having a first resource thereon, and a secondresource server having a second, different, resource thereon; and themethod further comprising having said director server be aware of whatresources are held on said first and second resource servers and uponreceipt of a request for one of said first and second resourcesselecting one of said first and second resource servers to serve outsaid requested resource and directing said request to said selected oneof said first and second resource servers, said demand server selectingan appropriate one of said first and second resource servers to receivesaid request using its knowledge of where the requested resource islocated, and further comprising dynamically distributing servableresources between available resource servers dependent upon demand forsaid resources, and varying the capacity of said resource serverscollectively to serve out demand for a particular resource dependentupon the demand for said particular resource.

[0074] According to an aspect of the present invention there is provideda method of satisfying a demand on a network for a network resource, themethod comprising providing the network with a demand director server, afirst resource server having a first resource thereon, and a secondresource server having a second resource thereon; and the method furthercomprising having said director server be aware of unusedresource-serving capacity of said first resource server and of unusedresource-serving capacity of said second resource-server, and saiddirector server upon receipt of a request for a requested resource whichis present on both said first resource server and said second resourceserver selecting a selected one of said first and second resourceservers to be the resource server that serves said requested resource,said director server selecting said selected one of said resourceservers using a knowledge of whether or not said first and secondresource servers have unused resource-serving capacity capable ofserving said requested resource, and further comprising dynamicallydistributing servable resources between available resource serversdependent upon demand for said resources, and varying the capacity ofsaid resource servers collectively to serve out demand for a particularresource dependent upon the demand for said particular resource.

[0075] According to an aspect of the present invention there is provideda method of sharing the demand for resources between a plurality ofnetworked resource servers comprising providing dissimilar resourcecontent on at least some different resource servers, having a knowledgeof what resource is available for serving out from which of saidnetworked resources servers, having a knowledge of said resourceservers' current capacity to satisfy a request for resources that theyare capable of serving, and allocating a request for a requestedresource to a selected resource server chosen with the knowledge that ithas said requested resource available for serving and that it has thecapacity to serve out said requested resource satisfactorily, andfurther comprising dynamically distributing servable resources betweenavailable resource servers dependent upon demand for said resources, andvarying the capacity of said resource servers collectively to serve outdemand for a particular resource dependent upon the demand for saidparticular resource.

[0076] According to an aspect of the present invention there is provideda computer readable memory device encoded with a data structure formanaging networked resources held on a plurality of resource serversconnected to a network, the resource servers having a plurality ofserver programs running thereupon; in respect to a change in networktraffic the data structure having entries, each entry containing:

[0077] a network address associated with a resource that is servableout; and

[0078] resource server-utilisation information or statistics.

[0079] According to an aspect of the present invention there is provideda method of making available computer network resources to users of anetwork comprising having a plurality of resource servers capable ofserving out a resource of a common kind, monitoring the demand for aparticular resource of said common kind automatically using a computer,and modifying overall capacity of said network to serve out saidparticular resource automatically in response to monitored or predicteddemand.

[0080] According to an aspect of the present invention there is provideda data structure for managing the automatic transfer of data between aserver program and a further server program in response to a change intraffic on a network, said data structure being arranged to manage thedistribution of the data over said server program and said furtherserver program, said data structure having entries, each entrycontaining:

[0081] a locator associated with said server program;

[0082] an identifier associated with at least a portion of said data;and

[0083] traffic statistics associated with network traffic to said serverprogram.

[0084] According to an aspect of the present invention there is profidedsoftware for controlling allocation of a request for a specific resourceon a network of resource servers to a selected resource server, thesoftware comprising a director adapted to direct said request to saidselected resource server, said director being adapted to receive a mapinput derived from a resource locator map adapted to provide networkaddresses at which specific resources are available for serving out, andsaid director being adapted to use said input to select an appropriateresource server that has said specific resource available on it forserving out and to direct said request to said appropriate resourceserver.

[0085] According to an aspect of the present invention there is profidedsoftware for controlling allocation of a request for a specific resourceon a network of resource servers to a selected resource server, saidsoftware comprising a director adapted to direct said request to saidselected resource server, said director being adapted to receive acapacity input derived from an evaluation of capacities of each of saidresource servers to serve out said specific resource, and said directorbeing adapted to select said selected resource server using saidcapacity input to establish that said selected resource server hascapacity to serve out said requested specific resource.

[0086] According to another aspect the invention comprises a method ofincreasing the number of different resources servable out from a webtier comprising having a web tier in accordance with the previous aspectof the invention and adding an additional resource server to said webtier, said additional resource server having additional resources notpreviously servable by said web tier.

[0087] A resource server's capacity to serve out a resource that it hasmay be dependent upon:

[0088] whether there is unused application software capable of servingout the requested search;

[0089] the amount of unused CPU processing power there is available;

[0090] the bandwidth available for serving out that resource from theresource server (which may be dependent upon which part, or parts, ofthe server can support the serving out of the requested resource).

[0091] The demand director may use information relating to one or more(or any combination of) the above in order to select which resourceserver will be chosen to serve out a demanded resource.

[0092] Information on what activity a resource serve is currentlyperforming, and possibly when it expects to be freed of that burden, isuseful to the demand director to enable it to evaluate the unusedcapacity of the resource server available to serve out additionalresources. An alternative to having the demand director evaluate theunused capacity of a resource server to serve out additional resourcesis for the resource server to evaluate that itself and inform the demanddirector of its unused capacity (instead of its used capacity).

[0093] Preferably network traffic associated with each resource serveris monitored by the demand director. Preferably the demand director hastraffic capacity limits for each type of resource available on eachresource director and uses these limits, along with a knowledge ofcurrent traffic for each resource server, to select which resourceserver will satisfy a particular demand for resources.

[0094] The method may include polling a resource server (or non-masterserver) by the demand director (or master server). The method mayinclude replying to the polling, by the resource server with informationrelating to any one or combination of the following: network addressassociated with the resource server, bandwidth utilisation of theresource server, resource served out by the resource server (either/or,or both, currently and since the last polling), a network address towhich the resource is being/has been sent, a price associated with theresource served.

[0095] The method may include generating billing information for a userby the demand director server. The method may include checking to seewhether a bill is due, by the demand director server. The method mayinclude billing the user.

[0096] The demand director may evaluate whether usage and/or networkcapacity information is within a predetermined limit. It may bedetermined whether a sever or server farm has spare data servingcapacity and may include copying a file thereto. A demand directorresource-location directory or database may be updated, typically withthe network address of the resource server with spare data servingcapacity, and an identifier associated with what resource is availablefor serving.

[0097] A further server may be connected to the network by the demanddirector, which may communicate, e.g. multicast, details of the newresource available and/or available bandwidth over the network. Themethod may include the storing of said details upon the demand director,or master, server and/or some or all other servers. The method mayinclude directing a request for the resource content of the furtherserver to the further server by the demand director server. The methodmay include varying the resource (e.g. data) content of the furtherresource server or by the demand director server dependent upon demandfor said resource content.

[0098] The method may include self-monitoring of the bandwidthutilisation of a resource server and may include determining if thebandwidth utilisation of the resource server is within a predeterminedlimit. The method may include passing an alarm message from the resourceserver to the master server, demand director, if the bandwidthutilisation is outside of the predetermined limit. The self-monitoringof a resource server/content server may constitute a separate invention,not necessarily linked with the previous invention(s).

[0099] The method may include self-monitoring of an input-output (10)port traffic by a resource server. The method may include transmittingthe results of the monitoring to the demand director, master server. Theresults of the monitoring may be compared to a statistical model, and itmay be determined if additional resource serving servers need to beconnected to the network, by the demand director, master, server. Themethod may include connecting an additional resource serving resourceserver to the network.

[0100] The method may include having a server farm (a “farm” is definedlater) and designating one of the servers of the server farm as amaster, or demand director, server. The method may include storing onthe master, or demand director, server a database containing details ofany one, or combination, of the following: a list of federated serverfarms and the network address of the demand director and/or resourceservers participating therein, resources potentially available on eachserver, network address of each resource server, current and/orhistorical usage statistics relating to each resource that can be servedout, current network traffic through an input-output (IO) device of eachresource server, the cost of accessing each resource, an identifier ofusers who have accessed any given resource.

[0101] The method may include setting a threshold level of networktraffic through each (IO) device. The setting of a threshold means thatproblems such as when the network, or an individual server, isapproaching its capacity can be determined early and extra resources orprocessing capacity added before the situation becomes critical.Typically, the IO device is a network interface card (NIC) or it may bean IO port, possibly of an NIC. The extra resources or processingcapacity may be added automatically by the demand director without humanintervention, or human intervention may be necessary.

[0102] The method may include resource servers informing the masterserver, or demand director, when the threshold level is passed. Themethod may include using the demand director's (or master server's)database to determine if there is an additional resource servingresource available within the network, or server farm, able to service arequest for the resource being served by the IO device.

[0103] The method may include generating a bill based upon a user'saggregate access of resources. The method may include providing acentral register of resources (e.g. data content) on a server farm, orfarms. This allows digital rights management to be centrally trackedthereby limiting the opportunities for piracy.

[0104] According to another aspect of the present invention there isprovided a computer readable memory device encoded with a data structurefor managing networked resources held on a plurality of resource serversconnected to a network, the resource servers having a plurality ofserver programs running thereupon; in respect to a change in networktraffic the data structure having entries, each entry containing:

[0105] a network address associated with at least one server resourceprogram;

[0106] an identifier associated with a resource that is servable out;

[0107] resource server-utilisation information or statistics.

[0108] The utilisation information or statistics may be associated withnetwork traffic through an input-output (IO) device associated with theresource servers.

[0109] The data structure may be arranged to facilitate the addition offurther entries relating to an additional resource server, those entriescontaining one or more of: an additional network address, identifier andresource-server utilisation statistics thereto. The resourceserver-utilisation statistics entries in the data structure may includeentries relating to any one, or combination, of the following: usage ofresources, access patterns for the resources, access times for theresources, outgoing bit rates. The data structure may be arranged tofacilitate a deletion of an existing entry therefrom. The data structuremay contain an entry containing a port identifier associated with eachresource. The port identifier may be a subset of the network addressentry.

[0110] The data structure may contain an entry relating to a thresholdlevel of network traffic associated with a particular resource on aparticular resource server. The data structure may contain entriesrelating to upper and lower threshold levels of network traffic forparticular resources on particular resource servers. Typically, thesethreshold levels will be expressed as a ratio of the theoretical toactual deliverable capacity of an input-output (IO) device, typically anetwork interface card (NIC).

[0111] Another thing that it is possible to do when there is a tier ornetwork of servers with different resources (e.g. data content) of thesame kind on them or associated with them, for example different videos,is to modify the capacity of the network to serve out a specificresource by replicating the resource and making it available fromdifferent, or more, servers on the network, or from different, or moreports on a server. This may make available different telecommunicationsbandwidth/routes, as well as increasing the overall capacity ofprocessing power capable of serving out the specific resource. Theoriginal resource may still be present and functional on its originalserver, or it may be removed therefrom during the migration ofdata/resource operation. Thus, typically (but not always) in response toan increased demand for a particular resource (e.g. a specific video)the resource may be made more available on the network. Since the demanddirector allocates request for a specific resource to a selected one ofthose servers capable of serving out the selected resource, it will beusual to update the demand director's load balancing data to associatethe addresses and capabilities of the server(s), or ports, to which thespecific resource has been migrated, or copied, to the places at whichthe specific resource can be found on the network—so that the demanddirector can take into account the fact that it has an increased rangeof options post-resource-migration.

[0112] According to another aspect the invention comprises a method ofmaking available computer network resources to users of a networkcomprising having a plurality of resource servers capable of serving outa resource of a common kind, monitoring the demand for a particularresource of said common kind automatically using a computer, andmodifying overall capacity of said network to serve out said particularresource automatically in response to monitored or predicted demand.

[0113] Preferably, the method comprises having a demand monitor servermonitor the demand for particular resources of said common kind, saiddemand monitor being aware of the capacity of each of said resourceservers to serve out additional servings, beyond a current level ofresource serving, of said particular resources. The demand monitor maybe aware of the capacity of each of said resource servers to serve outadditional servings of each of a plurality of user-selectable resourcespotentially available for serving out from each of said resourceservers. The demand monitor may also comprise a resource server.

[0114] Thus, the demand monitor is “others aware”—it knows thecapabilities of other servers (and of itself) to satisfy future requestsfor the serving out of each of different selectable resources of saidsame kind (e.g. different video movies).

[0115] The demand monitor may automatically cause additional capacity toserve out a specific resource to be created on said network, probably inresponse to monitored demand for said specific resource. However, saidadditional capacity may be created in advance of actual demand for it—inresponse to predicted future demand. The demand monitor may remove fromsaid network capacity to serve out a specific resource, possibly tofree-up serving capacity for a more popular resource.

[0116] The demand monitor may itself monitor what resources are beingserved out by what resource servers, possibly by monitoring traffic oninput/output ports of other servers, or a resource server may monitorits own resource-serving activities and provide information to saiddemand monitor regarding what it is serving and/or its capacity to serveout additional resources, preferably information indicative of itsability to serve out each specific resource of said common kindavailable on it for serving out.

[0117] According to another aspect the invention comprises a method ofmonitoring network traffic on a computer network comprising having anetwork of computers, or servers, and enabling the individual computersor servers to monitor their telecommunication activity on theirinput/output ports and report on their telecommunication activity to anetwork traffic monitor.

[0118] Thus resource, or content, servers may self-monitor their networkactivities and/or their capability to contribute further to serving outparticular resources.

[0119] The network traffic monitor may take an action automatically ifnetwork traffic for a computer or server is determined to be outside ofpermissible parameters. For example, if network traffic to a computerdrops to too low a level an automatic alarm may be raised.Alternatively, or additionally, resources potentially available forserving from the computer/sever with a reported drop intelecommunications activity may be automatically made available forserving from one or more other servers in the network. For example such“missing” resources may be made available by automatically migratingcontent/resources from the server that is experiencing a drop inserving-out abilities, or by obtaining the “missing” resources fromother places in the network (a record of what resources are available onwhat servers is typically kept on a demand director server). If theresources are kept on at least two different servers then a back-up copyshould be available to be the “seed” for copying to a new server, tocompensate for the degradation in service from the “missing”, orimpaired server.

[0120] According to another aspect the invention comprises a networkcomprising a plurality of content servers and a monitor server, saidmonitor server being capable of monitoring the network traffic to and/orfrom each content server, wherein said monitor server compares monitorednetwork traffic to a threshold level and upon traffic levels meetingsaid threshold level said monitor server is adapted to take an action.

[0121] Said action may be to increase the capability of the network toserve out content that is in demand.

[0122] Said threshold may comprise a level of capability of serving outcontent from a particular content server, and wherein upon a monitoredlevel of content serving reaching said threshold level, said monitorserver takes said predetermined action which comprises causing thecapability of said network to serve out said content to increase. Saidmonitor server may be adapted to copy said content to another networkedserver. Said servers may have telecommunication ports and said monitorserver may cause there to be an increase in the number oftelecommunication ports made available to a particular content of acontent server. Said threshold level may comprise a minimum activitythreshold level and wherein said action comprises performing adiagnostic check to ensure that said content servers are properlyoperational and/or communicated with said monitor server. Said minimumthreshold level may be assessed in many different ways, for example, athreshold for a particular resource, a threshold for overall networktraffic to a specific server, a threshold for all resources from aparticular port, a threshold for a specified resource from a particularport, or any other identified subset of measurable activity of saidservers.

[0123] According to another aspect the invention comprises a serverhaving a processor, a memory, and a self-monitoring software programcapable of being run by the processor, said monitoring program when runmonitoring levels of usage on applications servable out of said serverand being capable of identifying when the level of usage of saidapplications reach a threshold level and in response thereto causingsaid server to take an action which increases availability of saidapplication to a requestor who may request said application to be servedto them.

[0124] Said action may comprise copying said application to anotherserver.

[0125] When said server has a plurality of output ports and saidapplication is available on less than all of said output ports, saidaction may comprise increasing the number of output ports of said serverthat are capable of serving out said application.

[0126] According to the present invention there is provided a datacontent server comprising a processor, a storage device and aninput-output (IO) device (IO), the storage device having data contentstored thereupon and the processor being arranged to execute a monitorapplication that is stored upon the storage device, the processor beingfurther arranged to monitor the IO device when running the monitorapplication and to automatically determine whether a trigger conditionhas been met, and if so automatically to produce a control signalresponsive thereto.

[0127] Said control signal may comprise a replicate signal adapted tocause at least part of the data content of the data content server to becopied to a further server or made available at a further IO port onsaid server.

[0128] This arrangement allows the data content server to self manageand distribute content based upon the visibility of content use and itsability to deliver the data content. The data content server becomes‘self-aware’ for the purposes of application serving, typically basedupon bandwidth usage, and can replicate data content to further serversin order to provide scaleable serving. The further server may be aserver application that runs upon the data content server or it may be afurther data content server.

[0129] According to another aspect of the present invention there isprovided a data management system comprising a monitor unit and at leastone data content server, the monitor unit including a processor and astorage device, the server including an input-output device, and theprocessor being arranged to run a monitor application that is storedupon the storage device, and in which the processor is further arrangedto monitor the data content server's IO device when running the monitorapplication and to execute an action in response to a trigger conditionassociated with the IO device.

[0130] The monitor may itself he a resource server.

[0131] The data content server may have a processor arranged to monitorit's own IO device.

[0132] Typically the data stored on the servers will be file based datathat is readily partitioned and for which access patterns are known oris predictable, for example video or audio data. Alternatively the datastored on the servers may be block based, for example a section of adatabase stored across several compute units can be copied when one ofthe compute units is heavily accessed and the network configuration maybe altered appropriately.

[0133] The monitor unit may be arranged to monitor the server forfaults. Alternatively, or additionally, the server may be arranged toself-monitor for faults. The monitor unit may be arranged to monitor theserver ports and/or it may be arranged to monitor a client servernetwork connection. The monitor unit may be arranged to spawn anappropriate server application either on a further port of the server oron a further server. The monitor unit may be arranged to facilitate thereplication of the part of the data content of the server serviced by afailing port to a further server. This aims to ensure the continued andreliable supply of data to users. The monitor unit may update loadbalancing/routing tables which may be stored on the monitor unit. Themonitor unit may also comprise a director server of other aspects of theinvention, or indeed a resource server.

[0134] According to another aspect of the present invention there isprovided a method of data management comprising the steps of:

[0135] (i) monitoring traffic on at least one data content server on anetwork;

[0136] (ii) either or both of:

[0137] (a) starting up or shutting down an appropriate data servingapplication automatically upon a further server on the network inresponse to network traffic;

[0138] (b) copying at least part of the data content of the data contentserver to the further server;

[0139] (iii) updating routing/load balancing tables associated with thenetwork of resource servers; and

[0140] (iv) directing a portion of the network traffic to the furtherserver.

[0141] The method may include providing the server as a serverapplication upon the data content server or providing the server as afurther data content server.

[0142] The method may include copying the at least part of the datacontent from either of the data content server or an original datasource, for example a CD, DVD or tape media. This allows the data to becopied to the server even if the data content server has failed. Themethod may include executing steps (ii), (iii) and (iv) of the method inresponse to a change in network traffic due to any one of the following:application server failure, application server overload, insufficientnodes present upon a server based upon a statistical model. The methodmay include executing steps (ii), (iii) and (iv) of the method inresponse to a change in the number of active connections to a given porton the director unit. The method may include connecting or disconnectinga further server to/from a server farm in response to a variation innetwork traffic. The method may include configuring the further serverwithin the network environment.

[0143] According to another aspect of the present invention there isprovided a data structure for managing the automatic transfer of databetween a server program and a further server program in response to achange in traffic on a network, the data structure being arranged tomanage the distribution of the data over the server program and thefurther server program, the data structure having entries, each entrycontaining:

[0144] a locator associated with the server program;

[0145] an identifier associated with at least a portion of the data; and

[0146] statistics associated with network traffic between the serverprograms and the further server program.

[0147] The data structure may be arranged to distribute the data betweenthe server program in response to the statistics, typically to improvethe reliability of transfer of the data between the server program andthe client program. The data structure may be arranged to facilitate theaddition of further entries containing an additional locator, identifierand statistics thereto. The addition may occur in response to thestatistical entries in the data structure. The statistics entries in thedata structure may include entries relating to any one, or combination,of the following: usage of data, access patterns, access times, outgoingbit rates, accessed locations. The data structure may be arranged tofacilitate to deletion of an existing entry therefrom. The deletion mayoccur in response to the statistical entries in the data structure.

[0148] The data structure may contain an entry containing a portidentifier associated with each portion of the data, the port identifiermay be a sub-set of the network address entry. The data structure may bearranged to copy the portion of the data associated with a portidentifier from a first server program to a second program in responseto a variation in the statistics relating to the network traffic. In themost preferred embodiments there is a port per video being served.

[0149] By “port” is meant a part of a logical network address (e.g. port10020 from IP address 15.144.117.245). “Port” does not mean the networkcabling connector of the NIC card.

[0150] The data structure may contain an entry relating to a thresholdlevel of network traffic. The data structure may contain entriesrelating to upper and lower threshold levels of network traffic.Typically these threshold levels may be expressed as a ratio of thetheoretical to actual deliverable capacity of an input-output (IO)device, typically a network interface card (NIC).

[0151] The server program and the further server program may be residentupon the same network element. There may be a plurality of serverprograms.

[0152] It will be appreciated that in many aspects of the presentinvention it is intended that the data is managed with minimal,preferably no, human intervention.

[0153] According to another aspect of the present invention there isprovided a method of billing for access to data comprising the steps of:

[0154] (i) logging a request for data;

[0155] (ii) logging the origin of the request;

[0156] (iii) generating a bill from data stored on a database;

[0157] (iv) issuing the bill.

[0158] The method may include marking data at a given price for useand/or type of use. The method may include logging a user's identifier.

[0159] According to another aspect of the present invention there isprovided a method of data rental comprising the steps of:

[0160] providing a server farm according to another aspect of thepresent invention either as a stand alone or as part of a library;

[0161] servicing a request for data from a user of the farm; and

[0162] charging the user for the supply of data.

[0163] According to an aspect of the present invention there is provideda method of maintaining availability of requested network resourcescomprises having a network of servers each having associatednetwork-servable resources of a specific kind, and dynamicallydistributing servable resources between said resource servers dependentupon demand for said resources, thereby varying capability of saidnetwork as a whole to serve out a particular resource dependent upon thelevel of demand for said particular resource.

[0164] According to an aspect of the present invention there is provideda method of data management comprising the steps of:

[0165] (i) monitoring traffic on at least one data content server on anetwork and/or software application response time for an applicationsoftware running on at least one data content server on a network and

[0166] (ii) starting up or shutting down an appropriate data servingapplication automatically upon said server or upon a further server onthe network in response to network traffic and/or application responsetime.

[0167] According to an aspect of the present invention there is provideda network of resource servers each having deliverable resource of aspecific kind available for serving out, and a resource manager adaptedto receive a demand indicator input indicative of demand for aparticular one of said deliverable resources of said specific kind andto output a resource-varying output adapted to vary capability of saidnetwork as a whole to serve out said particular one resource.

[0168] According to an aspect of the present invention there is provideda network comprising a plurality of resource servers adapted to serveout servable resources of a specific kind;

[0169] a usage monitor; and

[0170] a resource manager;

[0171] said usage monitor being adapted to monitor usage of saidservable resources and to determine if a usage level of a particularsaid resource has changed significantly and to communicate such changesin usage level to said resource manager, said resource manager beingadapted to introduce an additional server to said network and/or startup a resource serving application on a networked resource server ifusage of said servable resources has increased significantly; and/orsaid resource manager being adapted to remove said specific resourcefrom a networked resource server and/or shut down a resource-servingapplication on a networked resource server if said usage of saidservable resources has decreased.

[0172] According to an aspect of the present invention there is provideda resource management server adapted for use with a plurality ofresource servers having resources of the same particular kind availablefor serving out, said resource management server being adapted toevaluate demand for a particular one of said resources of said specifickind, in use, in order to vary capacity of said network to serve outsaid particular one resource responsive to changes in demand for saidparticular one resource.

[0173] According to an aspect of the present invention there is provideda content management server adapted for use with a content servernetwork, said content management server comprising a servable contentmonitor adapted to monitor levels of usage of servable content of aspecific kind, and a content availability manager adapted to change theavailability of specific servable content depending upon demand for saidspecific servable content; said content management server being adaptedto introduce an additional resource server to a network and/or start upa content serving application on a content server if levels of usage ofa particular content have increased significantly, and/or being adaptedto remove content from a networked content server and/or shut down acontent serving application on a content server if levels of usage of aparticular content have decreased significantly.

[0174] According to an aspect of the present invention there is provideda resource management server adapted for use with a plurality ofresource servers having resources of a common particular kind availablefor serving out, said resource management server having demandevaluation means adapted to evaluate demand for a particular one of saidservable out resources of said specific kind, and capacity modifyingmeans adapted to modify capacity of said network to serve out saidparticular one resource, said capacity modifying means being responsiveto evaluated demand signals from said demand evaluation means.

[0175] According to an aspect of the present invention there is provideda network of video servers each having videos available for serving out,at least one of said video servers comprising a video migration manageradapted to receive video demand-indicative signals indicative of thelevel of demand on said network for said videos available for serving,and to cause either: (i) activation of video serving applicationsoftware on a video server which has a copy of said particular videoavailable, thereby making said particular video available for servingfrom said video server; or (ii) a particular video for which said demandis sufficiently high to be copied from a first video server where it isavailable for serving to a second, different, video server and to makesaid particular video available for serving from said second videoserver so as to increase the capacity of said network to serve out saidparticular video, or (iii) to cause a particular video for which saiddemand is sufficiently high to be servable out from an increased numberof port addresses of a said video server where said particular videoresides, thereby increasing capacity of said video server to serve outsaid particular video; or (iv) to be able to cause both any one of (i),(ii), or (iii) to occur, or any combination of (i), (ii) or (iii) tooccur; and wherein said video migration manager is adapted to operateautomatically without human intervention so as to dynamically distributevideo serving capabilities over said video servers of said network,responsive to demand for said videos.

[0176] According to an aspect of the present invention there is provideda video server for use with a network of video servers each havingvideos available for serving out, said video server being capable ofhaving videos available for serving out and further comprising a videomigration manager adapted to receive video demand-indicative signalsindicative of the level of demand on said network for said videosavailable for serving, and to cause either: (i) activation of videoserving application software for a particular video, for which demand issufficiently high, upon a video server that has said particular video inmemory; or (ii) a particular video for which said demand is sufficientlyhigh to be copied from a first video server where it is available forserving to a second, different, video server and to make available forserving from said second video server so as to increase the capacity ofsaid network to serve out said particular video, or (iii) to cause aparticular video for which said demand is sufficiently high to beservable out from an increased number of port addresses of a said videoserver where said particular video resides, thereby increasing capacityof said video server to serve out said particular video; or (iv) to beable to cause any one of, or any combination of, (i), (ii) or (iii) tooccur; and wherein said video migration manager is adapted to operateautomatically without human intervention so as to dynamically distributevideo serving capabilities over said video servers of said network,responsive to demand for said videos.

[0177] According to an aspect of the present invention there is providedsoftware for controlling the distribution of network resources overresource servers of a network, the software comprising a demandevaluation operative capable of establishing levels of demand forparticular resources available on said network, and a resourceallocation operative adapted to receive input from said demandevaluation operative and to cause: (i) resources to be copied from oneresource server of said network to another resource server of saidnetwork thereby to increase capacity of said network to serve out saidresource; or (ii) cause a specific resource to be started up and madeservable out from at least one additional port address of a resourceserver that already has said specific resource in memory so as toincrease capacity of said resource server to serve out said specificresource; or (iii) cause an additional server, not previously part ofsaid network, to be co-opted into said network so as to increasecapacity to serve out resources; or (iv) cause any one of, orcombination of, (i), (ii) or (iii) to occur.

[0178] According to an aspect of the present invention there is provideda network of video servers each having videos available for serving out,at least one of said video servers comprising a video demand manageradapted to receive video demand-indicative signals indicative of thelevel of demand on said network for said videos available for serving,and to cause either: (i) deactivation of video serving applicationsoftware on a video server which has a copy of said particular videoavailable, thereby making said particular video unavailable for servingfrom said video server; or (ii) to cause a particular video for whichsaid demand is sufficiently low to be servable out from a decreasednumber of port addresses of a said video server where said particularvideo resides, thereby decreasing capacity of said video server to serveout said particular video; or (iii) deleting from memory of a videoserver a video; or (iv) to be able to cause any one of (i), (ii), or(iii) to occur, or any combination of (i), (ii) or (iii) to occur; andwherein said video demand manager is adapted to operate automaticallywithout human intervention so as to dynamically distribute video servingcapabilities over said video servers of said network, responsive todemand for said videos.

[0179] According to an aspect of the present invention there is provideda video server for use with a network of video servers each havingvideos available for serving out, said video server being capable ofhaving videos available for serving out and further comprising a videodemand manager adapted to receive video demand-indicative signalsindicative of the level of demand on said network for said videosavailable for serving, and to cause either: (i) deactivation of videoserving application software for a particular video, for which demand issufficiently low, upon a video server that has said particular video inmemory; or (ii) deletion from a memory of a video server of a particularvideo for which said demand is sufficiently low so as to decrease thecapacity of said network to serve out said particular video, or (iii) tocause a particular video for which said demand is sufficiently low to beservable out from a decreased number of port addresses of a said videoserver where said particular video resides, thereby decreasing capacityof said video server to serve out said particular video; or (iv) to beable to cause any one of, or any combination of, (i), (ii) or (iii) tooccur; and wherein said video demand manager is adapted to operateautomatically without human intervention so as to dynamically distributevideo serving capabilities over said video servers of said network,responsive to demand for said videos.

[0180] According to an aspect of the present invention there is providedsoftware for controlling the distribution of network resources overresource servers of a network, the software comprising a demandevaluation operative capable of establishing levels of demand forparticular resources available on said network, and a resourceallocation operative adapted to receive input from said demandevaluation operative and to cause modification of capacity of saidnetwork to serve out particular resources, said modification comprisingan increase in capacity or a decrease in capacity to serve out aparticular resource.

[0181] According to an aspect of the present invention there is provideda method of serving out video over a network of video servers comprisingevaluating a capacity of said network as a whole to serve out specificvideo items by establishing for each video server in said network anestablished ability of each said server to serve out such said specificitems that are potentially servable from said each video server; usingsaid established abilities of each said video server to evaluate anoverall capability of said network as whole to serve out each of saidspecific video items; and taking steps triggered by said overallcapability of said network to vary said overall capability to serve outat least a selected one of said specific video items.

[0182] According to an aspect of the present invention there is provideda video server monitor for use with a network of video servers each ofwhich having video items, said monitor comprising an input adapted toreceive inputs, an output adapted to output outputs, and a processoradapted to process said inputs and generate said outputs, said inputsbeing representative of capabilities of each of said video servers toserve out video items potentially servable from respective said videoservers; and said processor, in use, being capable of evaluating anoverall capacity of said network from said inputs representative of eachindividual video server's capacity to serve out each said video item,and said processor being capable of using its evaluation of said overallcapacity of said network to control output of said outputs, said outputsbeing adapted to vary said overall capacity of said network to serve outa selected one of said video items.

[0183] According to an aspect of the present invention there is provideda network of video servers having video items available for serving, anda video server monitor, said monitor comprising an input adapted toreceive inputs, an output adapted to output outputs, and a processoradapted to process said inputs and generate said outputs, said inputsbeing representative of capabilities of each of said video servers toserve out video items potentially servable from respective said videoservers; and said processor, in use, being capable of evaluating anoverall capacity of said network from said inputs representative of eachindividual video server's capacity for each video item, and saidprocessor being capable of using its evaluation of said overall capacityof said network to control said outputs, said outputs being adapted tovary said overall capacity of said network to serve out a selected oneof said video items.

[0184] According to an aspect of the present invention there is provideda network of video servers wherein each video server is aware of its owncapability to serve out videos that it has, and is aware of a capabilityof each other networked video server to serve out videos that they have,and wherein one of said video servers assumes a role of master videoserving capacity controller and assesses a future capability of saidnetwork as a whole to serve out an additional copy of each video that ispotentially servable in said network, and compares this assessed futurecapability for each video with threshold capabilities for each video andupon said assessed capability reaching said threshold capabilities saidcontroller takes pre-programmed action automatically.

[0185] According to an aspect of the present invention there is provideda video server comprising processor means, memory means, andtelecommunication means; said memory means having, or being adapted tohave, video items for serving out of said video server; and saidprocessor means being adapted to cause a said video item to be locatedin said memory means and served out of said telecommunication means to anetwork; and wherein said video server has input means for inputting tosaid processor inputs indicative of an ability of other video serversnetworked to said video server to serve out video items held on saidother video servers, said processor monitoring an ability of said videoserver to serve out those of said video items held on said video serverand being adapted to monitor, from said inputs, abilities of said othernetworked video servers to serve out video items held on said othervideo servers; said video server thereby being adapted to monitor anability of said network to serve out particular said video items, andsaid processor having output means and being adapted to output outputsvia said output means for causing said network to have an increased orreduced capacity to serve out at least a specific selected video item.

[0186] According to an aspect of the present invention there is providedsoftware for running on a processor of a video server, said video serverhaving a memory containing video items, an input port, a control outputport, and a video streaming port, said software comprising a monitorroutine adapted to process signals received by said input port fromother video servers networked to said video server so as to establish anetwork-wide usage level of a plurality of videos items, or to establisha capacity of said network as a whole to serve out an additional copy ofeach of said video items potentially servable by said network; and saidsoftware having a video item availability-controlling routine which,pursuant to having established said usage level for each video item,causes actions to be taken to increase or decrease an ability of saidnetwork as a whole to serve out at least one specific video item.

[0187] According to an aspect of the present invention there is provideda method of modifying availability of video items on a network of videoservers comprising providing a network of video servers wherein eachvideo server is aware of its own capability to serve out videos that ithas, and is aware of a capability of each other networked video serverto serve out videos that they have, and wherein one of said videoservers assumes a role of master video serving capacity controller andassesses a future capability of said network as a whole to serve out anadditional copy of each video that is potentially servable in saidnetwork, and compares this assessed future capability for each videowith threshold capabilities for each video, and upon said assessedcapability reaching said threshold capabilities said controller takespre-programmed action automatically.

[0188] According to an aspect of the present invention there is provideda video serving system comprising a monitor unit and at least one videocontent server, said monitor unit including a processor and a storagedevice having a monitor application stored upon it, said serverincluding an input-output device, and said processor being arranged torun said monitor application, and in which said processor is furtherarranged to monitor said input/output device when running said monitorapplication and to execute an action in response to a trigger conditionbeing met associated with said input/output device.

[0189] According to an aspect of the present invention there is provideda method of modifying availability of video items on a network of videoservers comprising providing a network of video servers wherein eachvideo server is aware of its own capability to serve out videos that ithas, and an assessment of an aggregate capability of said network ismade by aggregating individual video server capabilities, and modifyingavailabilities of videos on specific video servers so as to modifycapability of said network as a whole to serve out specific particularvideo items.

[0190] According to an aspect of the present invention there is provideda method of maintaining availability of video farm or local area networkresources comprises having a farm or local area of networked videoservers each having associated network-servable videos and dynamicallydistributing videos between said video servers of said farm or localarea network dependent upon demand for said videos, thereby varyingcapability of said farm or local area network as a whole to serve out aparticular video dependent upon the level of demand for said particularvideo.

[0191] According to an aspect of the present invention there is provideda method of data storage management of data in a video farm or localarea network comprising the steps of:

[0192] (i) monitoring usage of video files;

[0193] (ii) determining if said usage of said video files has increasedor decreased;

[0194] (iiia) introducing an additional video server to said farm orlocal area network and/or starting up a video-serving application on avideo server if said usage has increased; and/or

[0195] (iiib) removing a said video file from a video server and/orshutting down a video-serving application on a video server if saidusage has decreased.

[0196] According to an aspect of the present invention there is provideda method of rich media data management comprising the steps of:

[0197] (i) monitoring traffic on at least one rich media data contentserver on a server farm or local area network and/or softwareapplication response time for an application software running on atleast one rich media data content server on a server farm or local areanetwork and

[0198] (ii) starting up or shutting down an appropriate rich media dataserving application automatically upon said server or upon a furtherserver on the farm or local area network in response to farm or networktraffic and/or application response time.

[0199] According to an aspect of the present invention there is provideda video farm or local area network of video servers each havingdeliverable video resource of a specific kind available for serving out,and a resource manager adapted to receive a demand indicator inputindicative of demand for a particular one of said deliverable videoresources of said specific kind and to output a video resource-varyingoutput adapted to vary capability of said video farm or local areanetwork as a whole to serve out said particular one video resource.

[0200] According to an aspect of the present invention there is provideda video farm or local area network comprising a plurality of videoservers adapted to serve out video resources of a specific kind;

[0201] a usage monitor; and

[0202] a resource manager;

[0203] said usage monitor being adapted to monitor usage of said videoresources and to determine if a usage level of a particular saidresource has changed significantly and to communicate such changes inusage level to said resource manager, said resource manager beingadapted to introduce an additional video server to said farm or localarea network and/or start up a video resource serving application on afarm or networked video server if usage of said video resources hasincreased significantly; and/or said resource manager being adapted toremove said specific video resource from a farm server or local areanetworked video server and/or shut down a video resource-servingapplication on a farm server or local area networked video server ifsaid usage of said video resource has decreased.

[0204] According to an aspect of the present invention there is provideda rich media content management server adapted for use with a rich mediacontent server farm or local area network, said rich media contentmanagement server comprising a servable rich media content monitoradapted to monitor levels of usage of servable rich media content of aspecific kind, and a rich media content availability manager adapted tochange the availability of specific servable rich media contentdepending upon demand for said specific servable rich media content;said rich media content management server being adapted to introduce anadditional rich media resource server to a network and/or start up arich media content serving application on a rich media content server iflevels of usage of a particular rich media content have increasedsignificantly, and/or being adapted to remove rich media content from anetworked rich media content server and/or shut down a rich mediacontent serving application on a rich media content server if levels ofusage of a particular rich media content have decreased significantly.

[0205] According to an aspect of the present invention there is providedsoftware for controlling the distribution of video serving applicationsover video servers of a video farm or network, the software comprising ademand evaluation operative capable of establishing levels of demand forparticular video serving applications available on said farm or network,and a resource allocation operative adapted to receive input from saiddemand evaluation operative and to cause: (i) video serving applicationsto be copied from one video server of said farm or network to anothervideo server of said farm or network thereby to increase capacity ofsaid farm or network to serve out video files in a particular format; or(ii) cause a specific video serving application to be started up toenable a video file to be servable out from at least one additional portaddress of a video server that already has a video serving applicationso as to increase capacity of said video server to serve out a videofile in a specific format; or (iii) cause an additional video server,not previously part of said farm or network, to be co-opted into saidfarm or network so as to increase capacity to serve out video servingapplications; or (iv) cause any one of, or combination of, (i), (ii) or(iii) to occur.

[0206] According to an aspect of the present invention there is provideda method of maintaining availability of requested network resourcescomprises having a network of servers each having associatednetwork-servable resources of a specific kind, and dynamicallydistributing servable resources between said resource servers dependentupon demand for said resources, thereby varying capability of saidnetwork as a whole to serve out a particular resource dependent upon thelevel of demand for said particular resource and wherein said resourceservers have port addresses and a particular resource servable from afirst port address is made available for serving from a second portaddress associated with the same server as said first port address.

[0207] According to an aspect of the present invention there is provideda method of maintaining availability of requested network resourcescomprises having a network of servers each having associatednetwork-servable resources of a specific kind, and dynamicallydistributing servable resources between said resource servers dependentupon demand for said resources, thereby varying capability of saidnetwork as a whole to serve out a particular resource dependent upon thelevel of demand for said particular resource and wherein an additionalresource server, not part of said network at a first time, joins saidnetwork in order to increase capacity of said network to serve out saidparticular resource, and wherein said additional resource server hassaid particular resource copied to it to enable said additional resourceserver to be capable of serving out said particular resource.

[0208] According to an aspect of the present invention there is provideda method of data storage management of data in a network comprising thesteps of:

[0209] (i) monitoring usage of a servable resource;

[0210] (ii) determining if said usage of said resource has increased ordecreased;

[0211] (iiia) starting up a resource-serving application on a resourceserver if said usage has increased; and/or

[0212] (iiib) shutting down a resource-serving application on a resourceserver if said usage has decreased.

[0213] According to an aspect of the present invention there is provideda method of data management comprising the steps of:

[0214] (i) monitoring traffic on at least one data content server on anetwork and/or software application response time for an applicationsoftware running on at least one data content server on a network and

[0215] (ii) starting up or shutting down an appropriate data servingapplication automatically upon said server or upon a further server onthe network in response to network traffic and/or application responsetime, wherein step (ii) is executed in response to a change in networktraffic due to any of the following: data serving application failure,data serving application response time, data serving applicationoverload of said server, insufficient servers having said data servingapplication present upon a server network based upon a statisticalmodel.

[0216] According to an aspect of the present invention there is provideda network of resource servers each having deliverable resource of aspecific kind available for serving out, and a resource manager adaptedto receive a demand indicator input indicative of demand for aparticular one of said deliverable resources of said specific kind andto output a resource-varying output adapted to vary capability of saidnetwork as a whole to serve out said particular one resource, andwherein said resource-varying output comprises a resource migrationsignal which causes said particular one resource to migrate from oneresource server to another server.

[0217] According to an aspect of the present invention there is provideda network of resource servers each having deliverable resource of aspecific kind available for serving out, and a resource manager adaptedto receive a demand indicator input indicative of demand for aparticular one of said deliverable resources of said specific kind andto output a resource-varying output adapted to vary capability of saidnetwork as a whole to serve out said particular one resource, andwherein said resource-varying output comprises a resource migrationsignal which causes said particular one resource to migrate from oneresource server to another server, and wherein said resource servershave port addresses and wherein said particular one resource isavailable for serving from one port address of a said server and whereinsaid resource varying output causes either (i) a second port address ofthe same said server particular resource available for serving; or (ii)a reduction in serving capacity of said network as a whole to serve outsaid particular resource by reducing the port addresses of a said serveroperating to serve out said selected resource down from a plurality ofport addresses to a smaller number of port addresses of that saidserver.

[0218] It will be understood that references to video both hereinbeforeand hereinafter are taken to encompass video (visual), audio and anyother streamed performances.

[0219] The invention will now be described, by way of example, withreference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

[0220]FIG. 1 is a block diagram of a prior art data storage system;

[0221]FIG. 2 is a block diagram of a plurality of networktelecommunications routes:

[0222]FIG. 3 is a schematic representation of a data storage systemaccording to at least one aspect of the present invention;

[0223]FIG. 3a is a schematic representation of a modified version of thedata storage system of FIG. 3;

[0224]FIG. 4 is a schematic representation of a request data packet;

[0225]FIG. 5 is a schematic representation of a video data packet;

[0226]FIG. 6 is a schematic representation of a networked video library;

[0227]FIG. 7 is a flow chart detailing a method of data managementaccording to an aspect of the present invention;

[0228]FIG. 8 is a flow chart detailing a method of data storagemanagement according to an aspect of the present invention;

[0229]FIG. 9 is a flow chart detailing a method of credit management fordata access according to an aspect of the present invention;

[0230]FIG. 10 schematically shows a web tier of Resource Servers inaccordance with one aspect of the present invention;

[0231]FIG. 11 is a schematic representation of a prior art long haulvideo serving arrangement;

[0232]FIG. 12 is a schematic representation of a prior art Ethernetenabled video serving arrangement;

[0233]FIG. 13 is a schematic representation of an embodiment of a videoserving arrangement according to an aspect of the present invention;

[0234]FIG. 14 is a representation of a routing/pricing table accordingto an aspect of the present invention;

[0235]FIG. 15 is a schematic representation of a long haul video servingarrangement incorporating an embodiment of the present invention;

[0236]FIG. 16 is a schematic representation of the video servingarrangement of FIG. 13 showing the ‘master’/‘slave’ video serverrelationship;

[0237]FIG. 17 is a schematic representation of a master-slave videoserving arrangement of FIG. 16 with a redistribution of files betweenservers;

[0238]FIG. 18 is a schematic representation of the video servingarrangement of FIG. 13 incorporating an additional data content server;

[0239]FIG. 19 is a flow chart of a method of data management accordingto an aspect of the present invention;

[0240]FIG. 20 is a flow chart of a functional step according to at leastpart of an aspect of the present invention;

[0241]FIG. 21 is a flowchart of a yet further functional step accordingto at least part of an aspect of the present invention;

[0242]FIG. 22 is a flowchart of a still further step functional stepaccording to at least part of an aspect of the present invention;

[0243]FIG. 23 is a flowchart of a yet still further step functional stepaccording to at least part of an aspect of the present invention;

[0244]FIG. 24 is a schematic representation of a prior art simplenetwork management protocol (SNMP) network management system;

[0245]FIGS. 25a and 25 b are prior art cluster arrangements for datamanagement;

[0246]FIG. 26 is a schematic representation of a data management deviceaccording to an aspect of the present invention;

[0247]FIGS. 27a and 27 b are schematic representations of other examplessimilar to that of FIG. 26;

[0248]FIG. 28 is a schematic representation of a data management systemaccording to an aspect of the present invention; and

[0249]FIG. 28a is a flow chart detailing a method of data managementaccording to the present invention.

[0250]FIG. 29 shows a LAN of video servers, comprising a video farm;

[0251]FIG. 30 shows a video server of FIG. 29;

[0252]FIG. 31 shows a monitoring routine of the video farm of FIG. 29;

[0253]FIG. 32 shows another monitoring routine of the video farm of FIG.29;

[0254]FIG. 33 shows schematically checking movie usage; and

[0255]FIG. 34 shows schematically checking bandwidth usage.

DETAILED DESCRIPTION OF THE DRAWINGS

[0256]FIG. 1 shows a typical prior art arrangement for infrastructurefor an internet service provider, for example an on-line retailer. Theinfrastructure typically comprises three layers, a web-tier 11, anapplication tier 12, and a database tier 13 connected by switches 14.The web-tier has a large number typically, 100 or 200 of highlydistributed servers 15 each with a small amount of attached storage(e.g. 100 GB) each having the same data content replicated thereupon toensure that a large number of external users can access the data (i.e.the same data can be accessed on a large number of servers 15, using aneven larger number of telecoms routes). The data upon the web-tier 11 isusually is the form of static hypertext mark up language (HTML) pages.The HTML pages do not require a great deal of memory. The applicationtier 12 has fewer servers 16 than the web-tier 11 and runs theapplications. A network switch, or router, 14 that sits above theweb-tier 15 directs external users to the web-tier server 15 that isnext in line for a request, load balancing the user request for dataover the servers 15 in a crude way. The database tier 13 has a verysmall number, typically only 1 or 2, large capacity servers 16 connectedto, high end large capacity e.g. hundreds of GB to tens of TB,consolidated storage elements 17 that are typically very expensive, e.g.$100 k high end disc arrays. The storage elements 17 contain datarelating to, for example user details, user profiles, stock and auctiondetails for the retailer. A user, referenced 5, accesses the data on theweb-tier 11 via the web-tier 11, the application tier 12, andparticularly via the switches or routers 14. The switches or routers aretypically level 2, level 3, or perhaps level 4, switches.

[0257] Each tier of the infrastructure processes the data as best it canand the passes the data down to the tier below it. One problem with thisapproach is the increasing cost of the lower tier devices coupled withthe need to replicate the devices at least once in order to build faulttolerance into the system.

[0258] Systems in which placement of network attached storage (NAS) atthe web-tier are used are not particularly efficient as the web-tierservers do not have sufficient network connections to satisfy theinformation demands placed upon them by users in such architectures (seefor example FIG. 2) and, NAS boxes have relatively few networkconnections. The cost of placing high end disc arrays, fibre channel andswitches in the web-tier is prohibitive due to the large number ofservers and the cost of Fibre channel adapter cards and disc arrays forthe web tier is simply uneconomic.

[0259] Each content, or resource, 15 server has identical contentcapable of being served out to the user 5. This reduces the datamanagement burden on the router/switches 14, allowing “dumber” switchesto be used.

[0260] In at least one embodiment of at least an aspect of the presentinvention the following definitions can be applied:

[0261] Server farm: a collection of servers acting together to provide agiven application type (for example video streaming). In manyembodiments of the invention a server farm will provide a load balanceddelivery of content to users requesting use of that content from thefarm. The user will, potentially, be able to access content on allservers of the farm using a single web address, so far as the user isconcerned.

[0262] Demand Director: a server acting as a management andco-ordinating station within a server farm for determining the locationof content across the servers of the farm, and capable of directing arequest for a specific resource to an appropriate resource server thatcontains that resource.

[0263] Resource Server: a server device capable of serving out aresource which can be requested by a user. Typically a general purposePC type hardware with some storage associated, e.g. internal disc,external disc array, in order to house the content, or resource, to bedelivered.

[0264]FIG. 2 illustrates a server 20 connected to a router 14 which isin turn connected to the internet by a plurality of differenttelecommunications links 22 a, 22 b, 22 c, 22 d, 22 e.

[0265]FIG. 3 shows a networked video server farm 302, in accordance withat least part of an aspect of the present invention, comprising adirector unit 304 and a plurality of resource servers 306 a-n. Insteadof “farm”, the reader could read “network”. A farm is a sub-class of anetwork, characterised by the servers all being “local” in the sense oflocal in telecommunications terms: i.e. they can communicate easily withthe requesting demand director. Often this is because they are trulygeographically local—e.g. in the same room or building, but “local” canmean “bandwidth/telecoms” local—i.e. good telecoms links between theserver and the demand director. The farm 302 is connected to an externalnetwork 308, typically the Internet or a MAN (Metropolitan AreaNetwork).

[0266] A typical server farm, say for serving out video movies, maycomprise around forty content, or resource, servers and a demanddirector in a nineteen-inch wide rack. The typical farm will be able tostore up to seven thousand feature length videos, each video being about2 GigaBytes (GB) in size.

[0267] The director unit 304 has an interface 309 thereupon whichspecifies upon which ports 310 a-c a resource-serving application islistening and which of the resource servers 306 a-n are able toparticipate in serving out that application resource. For example tworesource servers 306 b, 306 a are able to serve port 10045 requests forhypertext transfer protocol (HTTP) type application data (a resourcecapable of being served out), and all of the resource servers 306 a-nare able to serve requests for real time streaming protocol (RTSP)application data. Other ports may be able to serve file transferprotocol (FTP) requests. Thus there may be different categories ofservable resources, and each resource server may not be able to serveout all categories (or perhaps they can).

[0268] The video data can be partitioned into groups that are located ona per resource server basis. Serving the videos on a per resource server306 a-n basis allows a video to be tracked and a determination made asto how busy/popular any given video is.

[0269] The director unit 304 contains a database 311 which, in thecurrent embodiment, contains details of real time videos 312 a-h andupon which of the compute units 306-n the videos 312 a-h are stored. Thedatabase 311 can determine which resource server 306 a-n has a portsuitable for serving new content as it is introduced onto the farm 302.Typically, a video will stick to a specified port. Video operates in apredictable manner and is deterministic in nature, i.e. the input/output(10) requirements are well understood. For example, if a video is readback from a disc subsystem it is highly likely that the video will beread sequentially from the disc during playback. Thus, the capacity perresource server can be readily estimated. It will be appreciated thatthe data stored on the resource servers need not be video data: it maybe audio data or any other data set where data access patterns arepredictable and the data is readily partitioned, as the data is alreadydivided into objects—the files e.g. NAS devices that serve files canalso be implemented using this scheme in order to provide greaterscalability than is currently available.

[0270] Each resource server 306 a-n has two network interface cards(NIC) 313 a-b, one for communication with the demand director unit 304and one for outputting data to the network 308.

[0271] A user 314 connected to the network 308 requests a video 312 athat is stored on the farm 302. The request is passed from a user'sterminal 316 via the network 308 to the demand director unit 304. Thedirector unit 304 compares the request to the contents of the database311 to ascertain if the requested video (requested resource) is presenton the farm 302. If the requested video is not present on the farm thedemand director unit 304 returns an error message to the user 314.

[0272] Should the requested video be present on the farm 302 the demanddirector unit 304 accesses the database 311 in order to find a resourceserver 306 d that has the video stored upon it. If more than resourceserver 306 d, 306 j has the requested video upon it the demand directorunit 304 checks to see which of the resource servers 306 d, 306 j isbest placed to serve out the requested video. This load balancing istypically achieved by monitoring one or more of the bandwidth availableto a resource server, whether the resource server is currently beingaccessed either for the request severing out the same resource or forserving out another video, or possibly even projected accessrequirements based upon previous access demands placed upon a resourceserver. This load balancing is more sophisticated than the prior art“Round-Robin” or “response time” based approaches.

[0273] For example, resource server 306 f may have the most popularvideo 312 b stored upon it along with all of the other resource servers306 a-e, 306 g-n in the farm 302. The server 306 f may also have apreviously unpopular video 312 c stored upon it. The previouslyunpopular video 312 c may increase in popularity, with the increase inaccess being recorded at the director unit 304. Thus, when the nextrequest for the most popular video 312 b is received by the demanddirector unit 304 it knows that the computer unit 306 f is likely to beaccessed for the video that is increasing in popularity 312 c, and willtherefore use one of the other compute units 306 a-e,g-n to service thisrequest for the most popular video 312 b (assuming that they haveavailable unused serving-out capacity).

[0274] Once the demand director unit 304 has established which of theresource servers 306 a-n for example 306 d, it intends to service therequest for the video 312 a it strips TCP/IP address information 402from a data packet 404 containing the request, as shown in FIG. 4, andsplices a replacement TCP/IP header 402 a containing the network addressof the resource server 306 d to the payload of the data packet 404, asis known from standard routing techniques. The request data packet 404is forwarded to the compute unit 304, typically via an Ethernet link.

[0275] The resource server 306 d will have the desired video fileavailable for serving out to the user. As shown in FIG. 5, prior tostreaming the requested video directly to the user 316 the resourceserver 306 d rewrites a TCP/IP header 502 corresponding to the networkaddress of the demand director unit 304 to the payload 504 of eachoutgoing data packet 506 containing the streamed video data. The videodata will typically be in real time format, although it may be MPEG,Real Networks format or Windows Media format. The direct nature of thestreaming bypasses the demand director unit 304 resulting in the removalof a potential bottleneck in the data transfer. The data is usuallystreamed via a telecommunication network.

[0276] The effect of placing the network address of the demand directorunit 304 in the header 502 is to create a one time virtual connection318 between the user terminal 316 and the demand director unit 304. Thishides the network address of the resource server 306 d whilst allowingthe user 314 to play the video multiple times whilst the virtualconnection 318 is maintained, in a manner similar to the rental of videocassettes. However, once the ephemeral virtual connection 318 is brokenthe user 314 has no means of re-accessing the video without accessingthe demand director unit 304, as they do not know the network address ofthe resource server 306 d that served the data to them. This arrangementlimits the opportunities for a user to copy the data, or view it againat a later time, as the serving protocols are not the same as those usedby a NAS that serves out data as raw files.

[0277] One of the resource servers 306 a-n, or the demand director 304,can act as a billing unit 306 c. The user may be required to providedetails such as their e-mail address, address, telephone number and bankdetails before they are allowed full access to the farm 302. The billingunit 306 c receives information from the director unit relating to theusers details, the video that the user has requested and the cost ofviewing the video. Thus, the billing unit 306 c can automaticallyproduce and issue bills to users of the farm 302 based upon theirviewing habits. Where the users bank account details are retained by thebilling unit 306 c payment for viewed videos can be taken from a usersbank account. Typically billing occurs three days or so after viewingthe video or on a regular basis, for example monthly, and anysubscription fee for the use of the service can be billed at the sametime.

[0278] It will be appreciated that video clips can be provided as a‘free trial’ service for potential users of the video farm.

[0279] As the demand for a particular video increases the demanddirector 304 writes the popular video data to additional resourceservers 306 d-n that are within the server farm 302. Should the demandfor a video increase so much that there are not sufficient resourceservers 306 within the farm 302 the demand director 304 co-optsadditional resource servers 306 o-s to the server farm 302. Theseadditional compute units may be on other server farms connected to aMAN, as detailed hereinafter. Alternatively, they may be additional,non-utilised, resource servers associated with the farm 302.

[0280] The non-utilised compute resources are typically added to theserver farm 302 as demand begins to increase. The horizontal scalabilityof compute resources allows an xSP (e.g. SSP, ASP, ISP, or FSP) to startwith a small amount of relatively cheap infrastructure and increasetheir access provision in line with demand.

[0281] As will be appreciated, because there is asymmetric, different,data on the web tier resource servers 306, it is easy to add extra new,different resources, (e.g. videos). A new video, or other resource isprovided on a networked resource server 306 and the demand director 304is updated to be aware of the existence of the new resource capable ofbeing served out, and of its location on the network (so that it canaccept a request for the newly available resource and direct requests tothe correct resource server).

[0282] Similarly, it is straightforward to add additional servingcapacity. A new resource server is simply connected to the network andthe demand director informed of its existence/presence on the networkand what resources it has for serving out.

[0283] By way of example, new releases of video movies could simply beloaded into a new video server and the new server connected to thenetwork. Alternatively or additionally, old, unused, videos could beoverwritten with more popular videos, or newer videos. So long as thedemand director knows what is on the network capable of being servedout, and where it is, the demand director can communicate a user withrequested resource.

[0284] Altering the content servable out from a resource server may bedone with human intervention/manually, or a computer such as the demanddirector, may automatically re-distribute resources over the network inorder to be able better to serve out often-requested resources. This mayinvolve automatically copying resources either to provide multiplecopies of the resource with a resource server, or copies on anadditional, or different, server.

[0285] Once one is freed from the conventional straightjacket of havingall web tier servers have the same serverable content, things becomemuch easier to change. There is, of course, an increase in the overheadin managing the knowledge of what resource is where, and this requires asmarter demand director than the prior art. The decision to go againstthe conventional mantra that all resource servers capable of serving aparticular kind of resource (e.g. videos) have the same variety of andnumber of available resources of that specific kind of resource, hasvery significant advantages.

[0286] Returning to FIG. 3, as demand for a particular video decreasesthe demand director unit 304 removes this video data from some of theresource servers 306 k-n within the farm 302. Alternatively, the demanddirector 304 stops the unpopular application serving on the resourceservers 306 k-n and leaves the content in situ. Should the overalldemand for videos drop to a low enough level the director unit 304retires resource servers from the server farm 302. Those resourceservers that are retired can be recalled to the server farm 302 shouldthe demand increase again, or co-opted to other farms on a MAN, seehereinafter. Alternatively, or additionally, typically in the case of achronic shortage of disc space, the demand director unit 304 mayoverwrite unpopular video files, as determined by a statistical analysisthat it may perform on the existing resource servers 306 a-n with morepopular video files. Thus is it possible that any one of the resourceservers 306 a-n may have more than one copy of a video on it at anygiven time. More likely, however, is to have one copy of a specificvideo file on a video server and run more serving processes on the videoserver to serve out to different users, using the same video file. Anadvantage of having more than copy of a video file on the same server isso as not to overly tax the disc on which that video file is housed.

[0287] Thus, the server farm 302 is horizontally scaleable anddynamically expandable. This enables the provision of content levelgranularity. The amount of resource-serving capacity dedicated to aparticular resource (e.g. video) can be dynamically changed dependingupon demand.

[0288]FIG. 3a shows a modified version of a server farm 302 similar tothe server farm 302 of FIG. 3 in which three demand director 304∝a-c areprovided in order to build fault tolerance into the system 302′.Additionally, some of the resource servers 306′d-f have additionalstorage associated with them either in the form of DAS 320′ or NAS 322′.The DAS is typically connected to the units 306′d-f by a SCSI orEthernet link. Thus, the horizontal scalability of this arrangement isevident.

[0289] The demand director 304′a is shown servicing two requests fordata to two users 314′a,b via respective resource servers 306′b,d. Thedata is transferred to the users 314′a,b via respective networks 308′a,bin the manner described hereinbefore. The users 314′a,b start theirsession by connecting to the resource servers 306′b,d via the demanddirector unit 304′a. Thereafter the users 314′a,b are connected directlyto the resource servers 306′b,d.

[0290]FIG. 6, shows a MAN 602 having several server farms 604 a-dconnected thereto. Each of the farms 604 a-d has its own demand director606 a-d and resource servers 608 a-d, 608′a-d thereupon. Each of thedemand directors 606 a-d has a database 610 a-d that contains details ofthe video content of each of resource servers 608 a-d, 608′a-d. Thefarms 604 a-d are typically situated in multiple occupancy dwellings 611a-d such as condominiums or apartment blocks, usually in the basement orservice area. When one of the demand directors 606 a receives a requestfor a particular video it accesses database 610 a which is storedthereupon to see which, if any, of the resource servers 608 a-d, 608′a-dhas the required video data stored upon it.

[0291] If none of the resource servers 608 a-d, 608′a-d has the videodata the demand director 604 a issues a notification of that fact to theuser who requested the video. There may be multiple databases, forexample, each dwelling 611 a-d may have a self-contained farm and doesnot need to go outside its own farm to find content (videos). However, adwelling's farm may extract content from other dwellings' farms, asnecessary.

[0292] If at least one of the resource servers 608 a-d, 608′a-d has therequired video data upon it the demand director unit 604 a uses thedatabase 610 a to decide which of the resource servers 608 c, 608 b isbest placed to serve out the data, i.e. which resource server 608 c,608′b has the most available output bandwidth, which has its CPU notcurrently being over-used etc.

[0293] Once the decisions as to which resource server 608 c is accessedin order to fulfil the request for the data the databases 610 a-d areupdated to show the resource server 608 c as being utilised.

[0294] The packet headers sent between the demand director 606 a and theresource server 608 c, and between the compute unit resource server 608c and a requester 612 are re-written such that a virtual connection 614between the demand director unit 606 a and the user, and between theresource server and the user, is established as described hereinbefore.The packets appear to the recipient user to have come from the demanddirector, which is where the user was expecting them to come from.

[0295] The arrangement allows data content to be further distributedover the server farms 604 a-d forming a library without each farm havingto maintain the full data content of the library. For example a firstset of 100 different videos could be stored in one server and a seconddifferent, set of 100 videos (different from each other and from that ofthe first set) could be stored on a second server.

[0296] Data can be added to, or removed from each farm and additionalresource servers added or removed from the farms as describedhereinbefore.

[0297] Additionally, one of the demand director units 606 c can operateas a central billing facility where all requests for video, whereverthat request originates e.g. apartment building 611 a and whichever farm604 a-d services the request, are logged and billed. This centralbilling facility bills users of the system in the same manner as thebilling unit 306 c for the single server 302.

[0298] In both the individual farm, or the MAN connected library offarms, the content is loaded-onto the resource servers from a variety ofsources. For example the content can be loaded directly from a videocassette or DVD. Alternatively, the content may be downloaded onto theresource servers over a network, typically the internet from otherresource servers, or via a network (typically the Internet), from a filmstudio or film archive, or from a tape library connected to the serverfarm 302, or via a satellite download.

[0299]FIG. 7 is a flowchart detailing the methodology used in a serverfarm. The director unit 304 receives a request for a file (e.g. video oraudio) from a user (step 700), typically the user will be presented witha selection of videos from which to choose. The demand director 304accesses the database 311 in order to ascertain if the file is stored onthe farm (step 702). If the file is not stored on the farm the demanddirector 304 sends a notice to that effect to the user 314 (step 704).

[0300] If the file is stored on the farm the demand director 304accesses the database to check how many of the resource servers 306 a-nare available to service the request for the file (step 705) and logsthe request in a statistical model (step 706. Resource server 306 f hasthe requested file stored upon it. There are a number of optionsavailable to the demand director unit 304.

[0301] If the statistical model has calculated an increase in the numberof requests for the file and there is a possibility that the resourceserver 306 f may not be able to serve all of the requests for the file.The demand director 304 can copy the file to an additional resourceserver(s) 306 g-n the (step 708) and update its database 311 (step 709).Also, if the other resource servers 306 a-e, 306 g-n within the farm arenear their capacity the demand director unit 304 can connect toadditional resource servers, possibly having been previously retiredfrom the farm, in order to use their storage and connection capacity(step 710), and can copy the requested file to one of them (step 712)and update its database 311 (step 713). Alternatively the director unit304 can start up additional service providing applications on theresource servers 306 f.

[0302] Should the demand director unit 304 establish that there is morethan one resource server 306 f, 306 i capable of serving a request for afile the demand director unit 304 executes a load balancing routine(step 714) to ascertain which of the resource servers 306 f, 306 i isbest placed to serve out the requested resource, for example by lookingat the database in order to determine the current server activity, or byusing the statistical model, or it may use a simple round-robin scheme.

[0303] If there is no reason why the resource server 306 f is incapableof dealing with the request the demand director unit forwards a TCP/IPpacket of the request for the file (step 715) to a first, inward, NIC313 a of the resource server 306 f (step 716). Prior to outputting thefile the resource unit 306 f writes the TCP/IP header of the output datapackets such that it appears to the user's machine that they issue fromthe demand director unit 304 (step 718) thus establishing the one timevirtual connection 318 between the demand director unit and the user'smachine 316. The symbolic link creation is referenced as 720. Step 722outputs the file from the resource server 306 to the user via a suitableport of the second, outward, NIC 313 b, over the network 308. Theresource server 306 checks periodically, referenced 724, to see if someof the requested content is still to be served out. If there is stillremaining content the server 306 continues to re-write packet headers(718). If there is more content to serve out the network connection ofthe server 306 is closed down (referenced 726).

[0304] Once a resource server 306 f is found that can service therequest the file is sent via the network 308 to the user 314 asdescribed previously (steps 714720). The user is free to view the filefor as long as the symbolic link is maintained on the file system and aslong as the resource application being run on the resource server has afree resource to service the client's request. The symbolic link mayhave a time limit. The demand director unit 304 may include a trustedclock which is checked periodically to see if the symbolic link hasexpired (step 728). If the time limit for the link has expired thedemand director unit 304 issues an instruction to the resource server306 f to sever the link (step 730), i.e. remove the file system'ssymbolic link to the content or drop support for the resourceapplication being run on the resource server, typically by disabling theresource server's packet rewriting ability. Alternatively oradditionally, the resource server may by default remove the link after apredetermined time.

[0305] As a particular file becomes less popular the database willrecord less requests for it until at a threshold value, for example norequests within a week, two weeks or a month, the demand director 304will issue an instruction to a resource server 306 d which contains thefile to delete all but a single copy of the file (step 732) and whichleaves the content of the last copy of the video file of a server insitu on the server and shut down (step 734) the resource applicationrunning on the resource server 306 f. This process will continuerepeatedly over a period of time until all of the copies of the filehave been disabled from all of the resource servers 306 d, 306 k, 306 jthat had the file stored upon them (if demand falls off to the extent tojustify that). Alternatively, the threshold can be set such that all ofthe copies of the file are disabled from any resource server once thethreshold is passed. It is possible to delete a file from a resourceserver if it is unpopular, and this may be a preferred option sometimes,but since it is expensive in I/O telecoms to re-load a file to a server,it is usually preferred to de-select the file by closing the serving outapplication for that file running on the server.

[0306] Referring now to FIG. 8, the demand director 304 also monitorsthe total usage of the farm as the usage varies (step 802). As the totalnumber of requests for files decreases the director unit 304 moves filesbetween resource servers 306 to minimise the number of resource servers306 required to service the estimated number of requests for the files(step 804). This enables redundant resource servers 306 to be retiredfrom the farm 302 (step 806). The demand director unit 304 updates thedatabase to reflect the redistribution of files and the retired resourceservers (step 808).

[0307] As usage of the farm increases toward the capacity of theexisting resource servers 306 a-n the director unit 304 introducesadditional resource servers 306 o-s into the farm 302 (step 810) andcopies some of the files to these additional resource servers 306 o-s(step 812). The files copied to these additional resource servers 306o-s will typically be the most popular files. The demand director alsostarts up appropriate resource application serving programs on theresource servers 306 o-s upon their addition to the farm. However, thismay not be the case. If, for example, the additional resource servers306 o-s have a lower specification that those already in the farm 306a-n the demand director may copy less frequently requested files to theadditional resource servers 306 o-s to enable it to cause more copies ofthe most popular files to be created on the high specification resourceservers 306 o-s, in order to guarantee high quality access to the morepopular files. Once the additional resource servers 306 o-s have beenintroduced into the farm 302, their content and application servingcapabilities are uploaded into the demand director's database 311 (step814).

[0308] Referring now to FIG. 9, one of the resource servers 306 c, orthe demand director 304, can act as a billing unit. The billing unitlogs an incoming request for a file (step 902) including the networkaddress of the requesters computer and the requesters identification.The billing unit then causes bills to be issued to the user (step 904).The bill can be for access to individual file (step 906) typicallybilled by direct debit in three working days from a users bank account,the bank account details being held on a database. Alternatively, thebilling unit can produce a bill for the billing period (step 907)typically a day, or a week, or a month, and the bill can include asubscription charge, if one is levied. This ‘period’ bill can beautomatically deducted from a bank account (step 908) or sent to theuser for manual payment (step 910).

[0309]FIG. 10 shows a new web tier, referenced 1000, with resourceservers 15′ and a demand director 14′, as discussed, with differentresources of the same kind on the web tier servers 15′, and the demanddirector having a “map” of where to find requested resources.

[0310] It will be appreciated that it is new in a web tier of anApplication Service Provider to have a demand director know wheredifferent resources are non-homogeneously distributed over a pluralityof web tier servers, each of which has the same type of resourceavailable for serving (e.g. videos, audio, data records, streamed mediaproducts), but which have different resource content, all accessible toa user by inputting the same www address. This model is more flexiblethan the previously sacrosanct “all content-servers have the samecontent” model when it comes to expanding the availableresources/content (e.g. increasing the number of videos). It is notnecessary to modify existing web tier servers in order to add anotherwith different content. However, it may be desirable to do so to removeunwanted content from either being available for serving out—e.g. bystopping running the software necessary to serve out that unwantedresource, or removing it from the available resource database in thedemand director, or by deleting or overwriting the resource/content withmore desirable content. This avoids an increasing amount of infrequentlyaccessed content/resource—which is wasteful in memory and/or processingcapacity of the web tier servers.

[0311] It is known to have different web tier servers (accessible by thesame address as seen by the user) have different content/resources inthe sense of a first web tier server may have one category of resourceavailable for serving (e.g. music) and another may have a differentcategory of resource (e.g. car prices) but there has previously been aprejudice against having dissimilar source-category content/resource ondifferent web tier servers of the same ASP.

[0312] There may be a plurality of farms connected to a MAN. Each farmmay have a portion of data stored thereupon; the sum of the data storedon the farms may be a library.

[0313]FIG. 10 also illustrates, in principle, and in comparison withFIG. 3, using similar reference numerals, how simple the new arrangementis in comparison with the prior art of FIG. 3. The web tier 11,application tier 12, and database tier 13, and their associatedswitches, have been replaced by the single tier, web tier 1000, and therelatively dumb level 2, 3, 4 switches 14 have been replaced by a demanddirector, effectively level 7 switch 14′.

[0314] This makes it much easier for new companies to set up a web tier.They need to buy some resource servers (which could be practically PC'sor PC-like), and buy a demand director (which could also be a PC),install the appropriate control software, and install appropriateresources (e.g. videos). This is much easier, and cheaper, thanestablishing the complex and expensive infrastructure of FIG. 3. An ASPcould now be set up in a garage provided appropriate telecoms to the wwwwere available.

[0315] It will be appreciated that in practice it may be desirable tobuild in some redundancy to the demand director: perhaps have more thanone demand director, with one acting as a slave to the other until themaster develops a fault, at which point the slave, with mirror recordsand functionality, takes over. It may be desirable to have a copy ofeach resource on at least two resource servers (Raid 1 files in case aresource server develops a fault).

[0316] Partitioning the available resources onto different resourceservers works well with partitionable content/resources. Eachresource/content has an identify distinct from others in its class, andthis facilitates partitioning. A large integrated database may bedifficult to partition between different resource servers but perhaps itcould be done. Files are readily partitionable. The fact that in videoserving the resource is a datastream of content also makes it worthwhileto increase the complexity and overhead of finding the video on theweb-tier, because once a user is connected to the video resource theywill stay connected for a significant time whilst the video content isstreamed to them. If the content were of small size, and the user—webtier server connection time were small, the increase in data contentmanagement may not be worthwhile. In a typical example a user may stayconnected to a web-tier video steaming server for of the order of 10minutes, 20 minutes, 30 minutes, 60 minutes, 90 minutes, depending uponthe bandwidth of the telecoms and the size of buffer/memory available atthe user's end into which the video can be stored. As technologyimproves this time may be shorter.

[0317] The invention works well for read-only access to the resourceservers.

[0318] Whilst serving of video moves has been the main example it isalso envisaged that the invention can have significant uses in otherareas. As an example there is e-learning. Streaming a rich media product(e.g. video, audio, multi-media performance, etc.) using the inventioncan be used for teaching or training. Schools could use the invention,as could companies for corporate training/education. Tailored trainingpackages can be easily added to a website using the present invention—itis easier to change resource content with the present invention. A usercould receive an educational video; or an interactive session withstreamed rich media coming to him (e.g. video clips, pictures,questions, forms, music, games, etc.); or a non-interactive, read-only,session with the above. In a structured learning programme the ASP couldmake different modules available at different times (e.g. add morecomplex/higher level training after more basic training). The speed andease at which served out data content can be changed could be veryuseful.

[0319] There now follows a consideration in more detail of how theserving out of videos may be implemented in a Metropolitan Area Network(MAN).

[0320] Referring now to FIG. 11 which shows a prior art arrangement, along haul video serving arrangement comprises a video farm 1110, aserver local area network (LAN) 1112, typically an Ethernet, long haulinfrastructure 1114 typically a switched frame relay system, e.g. usingATM, such as SONET, a client LAN 1116 and a client machine 1118, or user1118.

[0321] The client machine 1118 issues a request for a video stored onthe video farm 1110. This request is passed over the client LAN 1116,the long haul infrastructure 1116, the server LAN 1112 to the video farm1110 where the request is serviced, i.e. the requested video file isaccessed. The file is transmitted from the video farm 1110 via theserver LAN 1112 to the long haul infrastructure 1114 where it is placedinto cells for transmission via the fast frame switched network to theclient LAN 1116. The transmitted data is reassembled at the interfacebetween the infrastructure 1114 and the LAN 1116. The client views thevideo on the client machine 1118.

[0322] This arrangement has the problem that the long haulinfrastructure 1114 is costly to install and maintain. Also thecellularisation of the data introduces a point at which transcriptionerrors can occur or data be lost.

[0323] Typically, long haul networks typically consist of networks thatare owned by telecommunication carriers. Data passes between thesecarriers' networks through peering relationships that are not activelymanaged and hence can cause quality issues such as packet loss.

[0324] Referring now to FIG. 12, another prior art arrangement, a numberof video servers 1120 a-d (resource servers) are connected to a LAN1122, typically an Ethernet. All of the servers 1120 a-d have the samevideo content 1124 a-e thereupon (in the prior art) and there is noawareness of load being placed upon any single server or file. This isthe current nature of video serving on LAN's, metropolitan area networks(MAN) and the Internet; massive over-provision of capacity in order toensure the availability of data to a client.

[0325] Referring now to FIG. 13, an embodiment of the present invention,a federated video serving arrangement 1300 comprises a plurality ofdistributed video servers, 1302 a-c, connected to a MAN 1304, a gateway1306 to the MAN 304 which is connected to a LAN 1308 having clientworkstations (users) 1310 a-c attached thereto.

[0326] A user on one of the workstations 1310 b requests a video. Therequest is transmitted over the LAN 1308, typically an Ethernet, to theMAN 1304 via the gateway 1306. The MAN 1304, which is also typically anEthernet, has the distributed video servers 1302 a-c connected thereto.One of the servers 1302 b acts as a master server, or demand directorserver, and the request for the video is forwarded by the gateway tothis master demand director server 1302 b.

[0327] The demand director master server 1302 b stores a table 1400, asshown in FIG. 14, having entries relating to a resource serveridentifier 1401 a network address 1402 associated with each resourceserver, typically an internet protocol (IP) address, each resourceserver's data content 1404, pricing information for each data file 1406,and the current bandwidth usage 1408 associated with each resourceserver. The demand director master server 1302 b interrogates the table1400 in order to ascertain which resource server 1302 a-c is best placedto service a request for data.

[0328] The resource servers 1302 a-c do not necessarily have the samedata content upon each of them. Indeed, it is usual that each server1302 a-c will have at least partially dissimilar content to any other ofthe servers in order to maximise the data content available over theMAN. In many instances different servers will have wholly dissimilarcontent thereupon, or at least substantially so. The MAN will typicallycover a conurbation and each of the resource servers will usually besituated in a separate building. The building is typically a multipleoccupancy dwelling, such as a condominium or an apartment building.Alternatively, the building may be a service provider's office or adesignated server building.

[0329] The demand director master server 1302 b and the ‘slave’ servers1302 a-c (resource servers) use an internet video streaming protocol(IVSP), that will be detailed hereinafter, in order to monitor the usageand manage the data content distributed over the servers 1302 a-c.

[0330] The master server 1302 b ascertains which of the servers 1302 a-cis best placed to service the demand and the video data is transmittedvia the MAN and Ethernet to the client machine 1118 using a packet basedtransmission protocol such as, for example, carrier sense multipleaccess with collision detection (CSMA/CD) or user datagram protocol(UDP).

[0331] The master server 1304 b updates the table 1400 in order toaccount for the request being serviced should a new request for data bemade. The table 1400 is updated using the protocol that is describedhereinafter.

[0332] Should the master server 1302 b fail or become disconnected fromthe MAN 1304 the slave servers 1302 a,c will detect this, as they willnot receive a reply to a request or response (that they periodicallysend out), and the first of the slave servers 1302 a to detect thefailure of the master server 1302 b will assume the role of master,demand director, server. The new master, demand director, server 1302 abuilds a table that is analogous to that held by the failed masterserver 1302 b by interrogating the remaining servers, in this examplethere is only the one remaining server 1302 c although there may be aplurality of other slave, resource-providing, servers.

[0333] The master server 1306 b can act as a centralised billing unitthat correlates a clients access to data with the cost of the data andgenerates a bill. The bill can be either sent to the client via E-mailor conventional mail, deducted directly from a client's bank account, oradded to the user's service provider's, or cable operator's, bill.

[0334] For example, a client's bill may be made up of 20% access toserver A, 5% to server B and 75% to server C. The master server 1306 baggregates this server usages to produce the client's bill.

[0335] In order to fulfil the billing role the master server 1306 b mustlog which video data the client accesses, the cost of accessing the dataand the clients network address, typically their IP address. If themaster server 1306 b is to send a bill to the client via conventionalmail it must retain the client's address and if it is to deduct the billdirectly from an account it must retain the client's bank details.

[0336] Referring now to FIG. 15, in a second embodiment of a federatedvideo serving arrangement a long haul data transfer arrangement 1500comprises a building 1502 having its own Ethernet LAN 1504 that isconnected to an Ethernet MAN 1506. The MAN 1506 has a plurality of videoserver farms 1508 a-c, as described hereinbefore, and another EthernetLAN 1510 connected thereto. The MAN 1506 is also connected to a longhaul digital network 1512, for example SONET, a synchronous digitalhierarchy (SDH) network or a frame based fast packet-switched networktypically based on asynchronous transfer mode (ATM). A second EthernetMAN 514 is also connected to the long haul network 1512 and has a videoserver farm 1516 and a building Ethernet 1518 connected thereto.

[0337] A user 1520, located in the building 1502 requests a video. Thisrequest is passed via the building LAN 1504 onto the MAN 1506. Therequest will either be addressed to one of the farms 1508 a-c or it willcirculate about the MAN 1506 until it identifies a video farm 1508 bwhich is capable of serving out the desired video. Once the request isreceived by the farm 1508 b the master server within the farm 1508 bconsults the table 1400 to ascertain which server has the requested fileand the available bandwidths to service the request.

[0338] Additionally, the table 1400 holds details of the data contentstored upon servers of the other farms 1508 a,c connected to the MAN1506, it may also retain the details of the data content stored on theserver if the video server farm 1516. Thus, if necessary, the requestcan be forwarded to the video server farm 1516 via the long haul digitalnetwork 1512 and the requested video can be served to the user 1520using both MANs 1506, 1514, the long haul digital network 1512 and thusto LAN 504.

[0339] Conversely, should a user on the building Ethernet 1518 request avideo that is present in one of the server farms 1508 a-c this can beserved in a manner similar to that hereinbefore described.

[0340] Referring now to FIGS. 16, 17 and 18, these show federatedservers as described in FIG. 13 and similar parts will be accordedsimilar reference numerals. As described hereinbefore the master server1304 b receives a request from one of the terminals 1310 c for a video.The master server 1304 b accesses the database 1400 to ascertain if oneof the servers 1304 a-c has the video data content upon it and if such aserver 1304 a has spare bandwidth available to stream the video to theterminal 1310 c. If the server 1304 a has the data content thereupon butdoes not have the bandwidths available for streaming purposes, e.g. allstreaming ports are at or near the capacity, but has bandwidth and orports available for, for example, file transfer protocol (FTP)transactions or for RSYNC, the master server 1304 b instructs the server1304 a to copy the requested data file to another server 1304 c withinthe farm 1300 with available streaming capacity.

[0341] Alternatively, typically if there are no servers currently withinthe farm 1300 with ports available for streaming or no availablestreaming capacity the master server can connect an additional server1304 d to the farm 1300 and transfer the requested file to theadditional server 1340 d in order to service the request.

[0342] However, if subsequently demand is seen to fall significantly,the data content can be consolidated on the original servers 1304 a-cand the additional server 1304 d can be returned from the farm 1300 bythe master server 1304 b.

[0343] In order to carry out a suitable method of data management uponthe arrangements detailed hereinbefore it is necessary to define a datamanagement protocol.

[0344] Referring now to FIG. 19, the master server (demand director)polls the slave servers (resource servers) periodically, typically everyfew seconds (Step 1900) in order to ascertain their bandwidth and portutilisation. The slave servers respond with details of their networkaddress, bandwidth utilisation, the videos streamed (both currently andsince the last polling), the address to which the streamed movies weresent and their price (Step 1902). If a server streaming data content toa user is polled for billing information the master server checks to seeif it has already received the information for that particular streamingof data from a previous polling in order to prevent multiple billingoccurring (Step 1903).

[0345] The master server evaluates the responses from the slave servers(Step 1904) and generates billing information for each user (Step 1906).The master server then checks to see if it is time to generate theperiodic bill for the user (Step 1908). If it is not time to issue thebill the master server waits a set time, typically a few-days, (Step1910) before again checking to see if it is time to bill. If it is timeto issue the bill to the user the master server generates an aggregatebill for the user for their data access wherever upon the network itoriginated and issues the bill (Step 1912).

[0346] In parallel with the billing function the master server evaluatesthe bandwidth usage and capabilities of each of the servers, i.e. whichservers have spare ports and bandwidth to output further videos (Step1914). The master server determines whether the usage of each of theservers, and possibly even each of the ports of IO devices of eachserver, are within a predetermined limit. (Step 1916). If the usage iswithin the predetermined limit the master server returns to polling theslave servers. Alternatively or additionally each server may evaluateits own bandwidth usage and capability to serve out.

[0347] Should the usage fall outside of the predetermined limit themaster server determines which server or servers have an appropriateport, or ports, and spare bandwidth to service the required file typesand copies the most heavily used video data file to a server or serverwith the appropriate port and spare bandwidth (Step 1918).

[0348] Once the master server has received an acknowledgement that thedata has been transferred to the appropriate slave server (contentserver) and has updated the database of distribution of content andnetwork address of content servers the master server returns to pollingthe slave servers.

[0349] One command associated with such an Internet video streamingprotocol (IVSP) is a “joining” command (IVSP-OP-JOIN) in which anadditional server is added to a server farm. Referring to FIG. 20IVSP-OP-JOIN comprises connecting a video content dataserver to thenetwork, (Step 2000). Once connected to the network the new video serverbroadcasts its data content and bandwidth available for streaming, andtypically also other types of data transfer, (Step 2002) in order thatthe master server can capture them and add them to the database thatretains details of which network address has which data content andavailable bandwidth (Step 2004). It is possible that servers other thanthe master server may also retain such tables and they too willauto-update on receiving the new video servers network address, datacontent and available bandwidths.

[0350] As server bandwidth usage increases it is necessary to compensatefor this for example by starting up additional application serverssoftware on existing video data content servers, migrating contentbetween video data content servers or connecting new video servers tothe video server farm. This requires a trigger, or alarm, command(IVSP-OP-BNDALARM).

[0351] IVSP-OP-BNDALARM, shown in FIG. 21, comprises a server monitoringeither its own or another servers bandwidth utilisation (Step 2100). Theserver checks to see if the bandwidth utilisation is within apredetermined threshold limit (Step 2102). If the bandwidth utilisationis within the threshold limit the server waits for a period (Step 2104),typically a few minutes before checking the servers bandwidthutilisation again. Waiting a few minutes between checking bandwidthutilisation prevents the network and/or CPU of the servers being swampedwith protocol execution and transport.

[0352] If this bandwidth utilisation is above the threshold limitindicating high usage, or below the threshold limit possibly indicatinga problem with the server, the server sends out an alarm message to themaster server (Step 2106). The alarm message will typically includedetails of the codes of videos currently being streamed from the server,the address to which they are bring streamed, the average bandwidthutilised by each movie being streamed and details of codes of videos inthe server that are not being streamed.

[0353] The master server accesses the database and evaluates which ofthe other available servers within the farm is suitable and has sparebandwidth, if any, for serving the data content of the heavily utilisedserver (Step 2108). The master server facilitates the copying of thedata content from to available, suitable server from the heavilyutilised server (Step 2110). The master server thus updates the databaseentries relating to the suitable servers content and the address for thecopied data content (Step 2112).

[0354] Referring now to FIG. 22, a message is sent from each server tothe master server detailing their respective usages (IVSP-OP-USAGE).

[0355] IVSP-OP-USAGE comprises each data server self-monitoring its owninput output ports traffic (Step 2200). These results are transmitted tothe master server (Step 2202) which compares the results to astatistical model of network traffic (Step 2204) in order to determinewhether or not to bring in additional data serving resources in theserver farm (Step 2206). If there is no need to bring in additionalresources the data content server returns to self-monitoring. Should themaster server determine that additional data serving resource isrequired the resource is connected (Step 2208). The additional resourcemay be either, or both, of server application software or an additionaldata content server.

[0356] In order to produce an aggregated bill for a user it is necessaryfor the master server to be aware of what data content is accessed fromthe slave servers by the user therefore a message must be transmitted tothe master server each time a user accesses the data (IVSP_OP_BILL).

[0357] IVSP_OP_BILL comprises the data content server receiving arequest for data from a user (Step 2300). A message containing detailsof the request are transmitted, via the network, to the master server(Step 2302). Typically, the details contained within the message includewhat video has been requested, or has been streamed, the network addressto which they were streamed, a user identifier and the price charged forstreaming the video.

[0358] Each user of the video farm will have an account which isestablished via the network, in a manner well known in network businessservices. The balance of a user account is debited each time the masterserver receives an access message with a user identifier correspondingto that account (Step 2304). The user account will typically be passwordprotected in order to prevent unauthorised access of files, for exampleaccess of 18 certificate videos by minors.

[0359] After one month an aggregate bill for all of the data accessed,from whatever source on the network, by a user is produced by the masterserver (Step 2306) and is sent to the user, either electronically ormanually (Step 2308). Although shown as occurring monthly the aggregatebilling can occur at any convenient interval, e.g. daily, weekly,fortnightly, etc. If a user gives their consent the master serverretains their bank account details and the aggregate bill is deducteddirectly from their bank account (Step 2310).

[0360] There are also message relating to a request for a copy of avideo to be sent to a data content server (IVSP_OP_COPY) andacknowledgement of such a request (IVSP_OP_ACK).

[0361] IVSP_OP_COPY request payload will typically include details ofthe video required, the coding format, e.g. MPEG, REAL MEDIA, encodingrates and file size.

[0362] IVSP_OP_ACK contains details of whether the server can servicethe request i.e. whether it has sufficient bandwidth available andwhether the server already has a copy of the data resident upon. If theserver does not already have a copy of the data resident upon the factthat it requires a copy to be sent to it in order to service therequest.

[0363] It will be appreciated that whilst the present invention has beendescribed with reference to video data it is equally applicable to anyfile based data type, for example audio data or computer based trainingmodules, and to non-file based situations.

[0364] There may be a counter which is arranged to increment each timedata is accessed. The farm may be part of a (Metropolitan area network)MAN. The farm may be situated in a residential building, typically amultiple occupancy dwelling (e.g. block of flats, condominium, officeblock). The farm may be an element in a video and/or audio rental or payper view system. The farm may include an automatic billing unit for saidrental or pay per view system. The billing unit may be arranged togenerate and/or distribute bills to a user of the rental/pay per viewsystem for content that they have accessed.

[0365] There now follows a description of another embodiment of theinvention, with an emphasis on a monitor server monitoring the availablecapacity of resource servers and/or traffic levels, and varying thecapacity of the network to serve out requested resource in response tothe level of demand of the resource in question. The monitor server maybe the same server as the demand director server referred to earlier, orit may not be.

[0366] It will be helpful to discuss the embodiment after a briefdiscussion of bow prior art networks manage demand for resources. FIG.24 shows a prior art network management system 2400 comprising amanagement console 2402 and a plurality of network elements 2404 a-e.The network element 2404 a-e are typically PC's, servers, disc arrays,tape drives and/or printers The network elements 2404 a-e are connectedto the management console 2402 via network connections 2405 a-e. Theseconnections need not, of course, be directly to the console 2402—so longas the network exists.

[0367] The management console 2402 typically displays a network elementidentifier (I.D) 2406 and its status 2408. The status display 2408usually takes the form of a series of colour coded screen regions 2410a-c. One of the regions 2410 a is highlighted to indicate the status ofthe network element 2404 c whose identifier 2406 is displayed. Typicallya red region indicates a faulty condition such as a server failure, ayellow region indicates a warning condition, for example high networktraffic and a green region indicates normal operating conditions. In analternative embodiment the management console may display a map of thenetwork and each network element is displayed in a colour appropriate toits operational status.

[0368] The above arrangement is limited in its functionality and doesnot remedy problems within the network as they arise: rather it alerts aperson, the network administrator, to the existence of the problem.Thus, the network still requires a great deal of slow, possibly flawed,human intervention in order to remedy any fault.

[0369] Referring now to FIG. 25a, this shows a prior art sharedeverything clustered (SEC) server arrangement 2500 in which two servers2502 a,b are connected to a network 2503 via a shared network connection2504. Both of the servers 2502 a,b share a common network switch 2506that connects them to a common storage device 2508. Any fault of thenetwork connection 2504, the network switch 2506, or the storage device2508, renders the arrangement 2500 inoperable. This is one of thereasons that clustered server arrangements require expensive, clustercertified components. Whilst increasing fault tolerance for the serversthis SEC arrangement does not increase tolerance to faults in thenetwork, storage or switches.

[0370]FIG. 25b shows a shared nothing clustered (SNC) server arrangement2501′ in which two servers 2502′a,b are connected to a network 2503′ viarespective, independent network connections 2505′a,b. Each of theservers 2502′a,b are connected to respective, independent storagedevices 2507′a,b that have mirrored data contents. A link 2509′ betweenthe servers 2502′a,b enables the servers 2502′a,b to monitor each othersoperational status. This arrangement requires expensive, clustercertified components and also there is a requirement to replicateinfrastructure in this arrangement thereby increasing costs above thoseof the SEC server arrangements 2500 of FIG. 25a. Additionally, half ofthe infrastructure and data storage capacity may remain idle at any onetime. Thus, this is a highly inefficient arrangement.

[0371] Referring now to the new arrangement of FIG. 26, a data content,or resource, server 2602 in accordance with the present inventioncomprises a housing 2604, a processor 2606, a storage device 2608 and anetwork interface card (NIC) 2610. The NIC has a plurality ofinput/output (IO) ports 2612 a-e. Typically, the ports 2612 a-e isconfigured to deliver a particular type of data content, or resource,that is stored on the storage device 2608, for example HTTP (hytertexttransfer protocol), RTSP (real time streaming protocol) or FTP (filetransfer protocol), to a network 2614.

[0372] The storage device 2608, which is typically a hard disc, has anNIC monitoring programme 2609 stored upon it that is passed to, andexecuted by the processor 2606 when running the programme. The processor2606 interrupts the NIC 2610 at regular intervals, typically every fewseconds and samples either or both of the outgoing bitrate or/and theincoming bitrate of the NIC. (Alternatively or additionally theprogramme may sample metrics previously collected by the operatingsystem). The processor 2606 compares the sampled bitrate to a reference,or threshold, bitrate stored within the programme. This referencebitrate can be varied in accordance with the type of NIC used and istypically a percentage of the ratio of the theoretical/actuallydeliverable bitrate capacity of the NIC. The interrupt frequency and thereference bitrate are usually set as default settings at the time ofproduction of the program but can be altered by a network administrator.

[0373] Should the sampled bitrate exceed, or alternatively fall, belowthe threshold reference bitrate the processor 2606 executes apre-programmed action. For example, when the server 2602 is servingvideo content the server 2602 is capable of serving a certain amount ofsuch requests. The processor 2606 samples the outgoing bitrate of theNIC 2610. As the NIC 2610 approaches its saturation level, typically60-75% of the theoretical/actual deliverable ratio, the referencebitrate threshold is passed and the server 2602 copies the content, orresource, that is needed to serve the requested video content to afurther server via the network 2614. The content copying is executed inorder to maintain the availability of the content (resource) to userswho may request it as a later point in time. The processor 2606 thensupplies the network address of the further server to loadbalancing/routing control, e.g. content-location director or tables forthe network, which may be held on the server 2602 or elsewhere on thenetwork (e.g. on a demand director server). Alternatively, oradditionally, the further server may update the load balancing/routingtables, wherever they may be held.

[0374] It will be appreciated that the monitoring performed bymonitoring programs need not be NIC usage level monitoring (or not onlyNIC monitoring), but could also be one or more of: local disc capacity,rate of local disc capacity growth/reduction over past set period (e.g.N seconds), NIC bandwidth growth/reduction over past set period.

[0375] As an even more concrete example, see FIG. 27a. This shows afirst server 2720 having a hard disc 2722, a processor 2724 and a NICcard 2726, and a second server 2730 network connectable to the firstserver 2720 via a network 2729, and also having similar components(which have been given similar reference numerals). Server 2720 isrunning load monitoring software 2709′ which notices when demand for aparticular application 2728, stored in server 2720 or on networkattached storage (NAS) accessed by server 2720, reaches a thresholdlevel. If demand for the application 2728 were to rise above thethreshold level the server 2720 would struggle to cope to serve out theapplication to meet higher levels of demand. The processor 2724 reactsto the demand for application 2728 reaching the threshold level bycopying the application 2728 to server 2730, via the network 2729, orjust starts it (the application) if the content is there already.Similarly, application software necessary to serve out a video mayalready reside on a server having the desired video file, in which casethe application software can be brought up to serve out the video, or toreduce the load on the server's CPU if the application software is notneeded at any particular time. If application software is not availableon a server it may need to be telecommunicated to it.

[0376] In this example, the server 2720 also updates a routing,directing, or load balancing directory/database 2742 in a directorserver 2740 attached to network 2729 to inform the director server thatapplication 2728 is now available on both server 2720 and server 2730.Thus, when a request to serve out application 2728 is received by thedirector server 2740, it now can choose to direct the request to server2720 or server 2730, depending upon which it believes can serve out therequested application satisfactorily.

[0377] The application 2728 could, for example, be a video performance,say purely for example the latest James Bond film. The dynamicgeneration of extra resource (or application) serving capacity, in realtime, without human intervention, allows a network to be dynamicallyhorizontally scaleable. That is to say, simply by attaching extraservers to the network and moving around and/or creating extra copies ofrequested resource/applications (which need not involve attaching extraservers), it is possible to increase the ability of the network as awhole to serve out particular resources or applications.

[0378] It will be appreciated that the threshold, or trigger, level ofdemand on server 2720 could be one or more of: a certain level ofprocessing power capacity required; a certain level of access oftelecommunications channels to serve out the application; a certainlevel of bandwidth availability in the telecommunications channels. Thusthe application may be copied to another server (or run on a furtherport (logical network address) on the same server) because the processor2724 cannot cope with too much additional demand, or because thetelecommunications network relating to server 2720 is under strain (e.g.NIC and 2726 may be approaching capacity).

[0379] It will also be appreciated that although the above discussescopying application 2728 to another server, server 2730, it could becopied or otherwise made available internally of the server 2720 (andany NAS linked to server 2720) so as to increase the capability of theserver 2720 to serve out additional application 2728. For example,application 2728 could be originally served out of only one NIC port (inthe sense of part of a logical network address), but later, at increasedlevels of demand for application 2728, it could be served out of two, ormore, ports on the NIC of server 2720.

[0380] In cases where particular applications, for example data files,are associated with a particular port 2612 a the processor can monitorthe particular port 2612 a and copy the application data to anappropriate port on a further server, i.e. one that is configured todeliver that particular type of data, if the port on the first server isreaching saturation.

[0381] The server 2602 may also be configured to spawn an appropriateapplication programme on the further server (e.g. server 2630) in orderto allow the copied data content to be delivered, should the furtherserver not already be configured to deliver the data content. That is tosay if the further server already has the software necessary to serveout data content that is copied to it, it is unnecessary to copyoperating software, but if it does not have the requisite operatingsoftware that will have to be copied as well as the subject matter datacontent.

[0382] The processor 2606 can also compare the sampled bitrate with alower threshold level below which it is expected that the NIC 2610bitrate will not drop. Should the sampled bitrate fall below this lowerthreshold limit the processor 2606 runs a diagnostic code in order todetermine if there is a fault, if 10 traffic has just decreased, orwhether to use a lower serving capacity on that server. If there is afault the diagnostic code will typically identify the likely faultsource(s) and report it (them) to a system administrator.

[0383] It is possible, in an alternative embodiment, that the server2602 may have more than one NIC. In this embodiment the processor canmonitor one, some or all of the NIC's. Each NIC may have its own uniquethreshold limit or some, or all NIC threshold limits may be the samedepending upon the types of NIC used.

[0384]FIG. 27b shows a server 2750 having a hard disc 2752, a processor2754, a first NIC 2756 and a second NIC 2757. An application 2758, inthis case a video movie, resides on the hard disc 2752. Self-monitoring“capacity to serve out” software 2709′ is running on server 2758 tomonitor when the server is likely to encounter difficulty in serving outapplication 2758 via original NIC 2756. When a threshold level ofdemand/serving capacity is reached the software 2709′ causes application2758 to be copied again in the hard drive 2752 and the copy, referenced2758′, is used to serve out the same application 2758, but via thesecond NIC card 2757. Thus, the server 2750 now has a much greatercapacity to serve out the resource that is application 2758 (possiblytwice the capacity, or even more, depending upon the bandwidth andprocessing power allocated to NIC 2757).

[0385]FIG. 27b also illustrates the point that the disc drive 2752 doesnot only have the one application 2758 on it, it has others, only one ofwhich is shown as application 2755. In a similar manner to thatdescribed above, software 2709′ also monitors usage of application 2755and if extra serving-out capacity of application 2755 is required itcauses it to be copied and made available for serving out, either via anadditional port on NIC 2756 or via second NIC 2757 (or both).

[0386] Referring now to FIG. 28, a server farm 2802 comprises a directorunit 2804 and a plurality of servers 2806 a-e. The director unit 2804comprises a data storage device 2808, typically a hard disc drive, aprocessor 2810 and an NIC 2811.

[0387] The servers 2806 a-e comprise data storage devices 2812 a-e,typically hard disc drives, and NICs 2814 a-e. The servers 2806 a-e areconnected to a network 2816 via their NICs 2814 a-e, each NIC 2814 a-emay have a plurality of IO ports 2817.

[0388] The director unit's storage device 2808 has a monitoringprogramme 2818 and a load balancing/routing table 2820 stored thereupon.When executed on the processor 2810 the monitoring programme interruptsthe NIC's 2814 a-e of the servers 2806 a-e in order to sample theiroutgoing bitrate. If the sampled bitrate is above a pre-determinedthreshold or below a different predetermined threshold the processorexecutes an action, as will be described in detail hereinafter. Thethreshold level is typically a percentage, for example 80% of thetheoretical/actual deliverable bitrate for any particular NIC 2814 a.The frequency of the interrupts and the threshold levels are initiallyset by the vendor but are typically subsequently alterable by a user.Suitable threshold altering input devices (e.g. a keyboard) areconnectable to the server, and suitable threshold-altering softwareresides in the server.

[0389] The monitoring programme 2818 is usually written in a scriptedlanguage that does not require recompilation prior to execution andconstitutes a control language rather than an application language. Thismakes the programme 2818 flexible and powerful as it has directimplementational effect upon the system that it is intended to control.

[0390] The load balancing/routing table 2820 contains details of whichresources or applications, e.g. portions of data, are stored on whichserver 2806 a-e. This arrangement is of particular importance if thereis dissimilar data content distributed over the individual servers 2806a-e of the server farm 2802, i.e. the data is not merely mirrored acrossall of the available servers 2806 a-e of the farm 2802: one server canhave different data on it to the other servers—indeed many or all of theservers may have largely different data on them (e.g. different videomovies). The table 2820 can also include an indicator of which port 2817a file is associated with.

[0391] In one more concrete example of FIG. 28, the network of servers2806 a to 2806 e comprise a Video Farm 2830: a collection of serversnetworked together and all serving out the same type of resource: videomovies, and all accessible by a common input address for a resource(video) requesting party. A customer, referenced 2832, enters theaddress of the Video Farm 2830 over the Internet, (represented asnetwork 2816). This request is conveyed to the director unit 2804. Thedirector unit knows which video movies are present on which servers 2806a to 2806 e. The director unit knows the remaining unusedresource-serving capacity of each of the servers 2806 a to 2806 e, andit can load balance the request. Load balancing means that the directorunit decides to which server to send the request for the serving out ofthe requested resource weighting the current availability of resourceand capability of the servers to serve it out successfully, and possiblyeven with a knowledge of future likely resource-serving capacity of theservers. For example, the director unit may simply direct the request tothe server which has the most present, current, capacity to serve outthe resource—assuming of course that there is more than one server withthe requested resource/video available. However, the load balancingcould possibly be more sophisticated and could take into account futureavailability—for example if right now server 406 b had two minutes of amovie left to play, and for server 2806 b to accept the request to serveout a further requested movie to a new customer would take it muchcloser to its saturation threshold then if server 2806 c dealt with thenew request, server 2806 b may nevertheless still be allocated the newrequest to serve out if in two minutes time its available capacity willrise above the level available on server 2806 c when server 2806 b stopsserving out the movie that has newly finished. This may be attractive ifserver 2806 c has a popular movie on it that is likely to be requestedagain soon, and it is desired to keep serving capacity of server 2806 cavailable for that eventuality.

[0392] If there comes a time when one of the servers, say server 2806 a,gets to its threshold level of serving capacity the server 2806 a, orthe director unit 2804, causes one or more of the resources of server2806 a to be copied to another server, say server 2806 e, so as toincrease the capability of the Video Farm as a whole to serve out theresources/video movies that are in demand.

[0393] Copying video movies from one server to another, or from one portto another, may of course reduce the ability of the Video Farm as awhole to serve out other, less popular, videos as the memory thatcontains the less popular video is overwritten with more popular video,and./or as telecoms bandwidth is preferentially allocated to, orreserved for, popular videos.

[0394] Thus, the capacity of the Video Farm 2830 to serve out aparticular video movie is dynamically and automatically adjustable,depending upon demand.

[0395] Furthermore, the Video Farm can co-opt another server, not in theVideo Farm at a first moment in time, but networked to or communicablewith, the Video Farm. It can therefore dynamically increase its overallcapacity to serve out videos (or network resources). It is horizontallyscalable. This is illustrated in FIG. 28 by server 2840, which isconnectable to the Video Farm. The director unit 2804 knows the addressof server 2840.

[0396] As resources, e.g. video moves, are moved around between servesthe load balancing address list 2820 is updated to reflect the currentaddresses and capacity.

[0397] The director unit 2804 (or a unit that does no demand directing)can also be utilised in a fault monitoring role. For example, thedirector unit 2804 monitors the average data traffic within the farm2802. Should the average data traffic fall below a threshold, belowwhich it should never fall, the processor 2810 runs a diagnostic code inorder to determine whether a fault has occurred or whether it is just anunusual lull in network activity. As well as determining if a fault hasoccurred the diagnostic will usually attempt to determine the source(s)of the fault and notify a systems administrator of them.

[0398] In an alternative, or additional, fault monitoring role thedirector unit (or a monitor unit) 2804 monitors network connections 2822a-e to the servers 2806 a-e and the usage of the data content of theservers 2806 a-e. This monitoring will typically be on a per-port (partof IP address) basis as each content type, for example HTTP, FTP, RTSP,typically requires an IO port (referenced as number 2817) to beconfigured for delivery of the content (this is not the same as a portupon which an application is running). For example, HTTP content istypically served on I/O port or connector 2880, FTP on I/O port orconnector 2821 and RTSP content is served on another port or connector.Typically in the case of file based data, for example, video and/oraudio data, each file is associated with a particular I/O port orconnector. It is possible to have multiple instances of copies of thesame file being run from multiple ports or connectors on a singleserver.

[0399] The director unit 2804 retrieves the utilisation information fromthe respective NICs 2814 a-e of the servers 2806 a-e. Upon noting a dropin utilisation of a network connection 2822, possibly denoting a problemwith a server or a failure of a server to respond to an interrogationsignal, denoting a possible server failure, the director unit 2804instigates a transfer of the data content that is unique to the server2806 a to a secondary server 2806 b (as denoted by the arrow A in FIG.28). If the secondary server 2806 b does not have the correctapplications to service the data from the failed server 2806 a thedirector unit 2804 spawns the requisite applications, subject tocopyright considerations, on the secondary server 2806 b. If it is notpossible to copy the data from the server 406 a the director unit canaccess the data from its original source, for example a DVD, CD or tapemedia. The availability of the same data that is on a failed server, orthe data on a server that cannot be accessed due to a telecoms failure,is assumed. A reference data store (not shown) is provided to enable thecontents of the downed server to be recreated on a “live” server.

[0400] Once the transfer of data and applications has been completed thedirector unit 2804 updates the load balancing/routing table 2820 withthe network address of the secondary server 2806 b and the identity ofthe files, and where applicable a port identifier.

[0401] The director unit 2804 can also be used in high level usagemonitoring, in which the director unit 2804 monitors the connections to,and usage of the content on, the servers 2806 a-e. This monitoring maybe carried out on a per port basis as detailed hereinbefore. Forexample, if one of the servers 2806 e is serving video data the servercan only serve a certain amount of 28.8 Kbps video channels from anyNIC. As one of the servers 2806 e becomes busy, i.e. exceeds thepredetermined threshold for its NIC 2810, or receives more requests fora file associated with any port 2817 than it can service, the directorunit 2804 co-opts an additional server 2806 f into the farm 2802 andfacilitates the copying of part of all of the data content of the busyserver 2806 e to the additional server 2806 f (as denoted by the arrow Bin FIG. 28).

[0402] Although described as a software based implementation it will beappreciated that the ‘programme’ 2818 can be implemented by any suitablehardware or firmware arrangement.

[0403] Referring now to FIG. 28a, for a server a processor monitors thetraffic output via the ports of a NIC (Step 2850). The NIC may be partof a data content server that is associated with the processor and theprocessor may be monitoring the status of its own NIC. Alternatively,the processor may form part of a director unit and may be arranged tomonitor an NIC associated with a server that is remote from it.

[0404] The processor checks to see if the network traffic on a givenport, monitored at the NIC, has risen or fallen (Step 2852). If theprocessor notes a fall in the network traffic below a predeterminedthreshold it may issue an instruction to the NIC to shutdown a dataserver application on the port associated with fall in network traffic(Step 2854). If the processor notes a fall in network traffic across allof the ports of a NIC the processor may issue an instruction todisconnect the server from the network (Step 2856).

[0405] If the processor notes an increase in the network traffic on agiven port it checks to see if there are any available ports on the NICthat are capable of serving the same format of data as the busy port(Step 2858). If there is an available port(s) capable of serving theformat with spare bandwidth the processor starts up a data serverapplication on the available port (Step 2860). The processor facilitatesthe copying of the data associated with the busy server's port to theavailable port (Step 2862).

[0406] If there are no ports available that are capable of serving thesame data format as the busy port the processor issues an instruction tofind a further server on the network with an available, suitable port(Step 2864). Once the further server has been found the processor checksthe further server to see if it has the required data server applicationpresent upon the suitable port (Step 2866). If the suitable port doeshave the required data server application thereupon the processorfacilitates the copying of the data associated with the busy server'sport to the suitable port (Step 2868). The processor facilitates thedata copying either by direct involvement in the copying process or byissuing an instruction to the busy server to copy the data to thefurther server.

[0407] If the further server's suitable port does not have the requireddata server application the processor facilitates the copying of thedata server application to the suitable port (Step 2870), again eitherdirectly or indirectly. The processor then facilitates the copying ofthe data to the suitable port (Step 2872) as described hereinbefore.

[0408] After completion of the above mentioned actions associated witheither a fall or a rise in network traffic a database, that contains thelocation of data on the network, typically as a network address and aport identifier, and the results of the monitoring of the networktraffic, is updated (Step 2874). The table is typically used as arouting and/or load balancing table by a director class server or loadbalancing switch.

[0409] Another area of use for the present invention is in data logging.The average traffic over a network should not normally fall below acertain level. A monitor server can be set up to watch the level ofnetwork traffic and have a minimum traffic level threshold entered intoit (possibly an updateable/re-settable threshold). If the thresholdlevel is ever reached this could trigger diagnostic code, based uponthat threshold, to determine whether there was a problem or not. Theremay be reasons why traffic will reduce without there being a systemproblem (e.g. Christmas Eve, Christmas Day).

[0410] It will be appreciated that hitherto it has not been possible tohave cheap enough scalable content layer/tier of content servers, andthat by allowing dissimilar content we achieve ready scalability. Beingable to bring into a network new servers, with new content (contentlevel granularity) is attractive. Furthermore, whilst rudimentaryload-balancing demand directors are known, none have content and/orapplication awareness: they do not know what content is where and/or howbusy is a server to which a request could be directed. We can add newservers for specific functionality and content can be put onto them toalleviate demands on, for instance, a server serving a particular videostream that is requested by users frequently.

[0411] We may well wish to provide a content-type farm (a collection ofservers acting together to serve out a given resource (or application)type (e.g. video streaming 1). The farm may provide a load-balancedservice.

[0412] Dynamically distributing content over available networked contentservers so as to maximise performance of the network to serve out thecontent is a broad concept. A content server may be “self-aware” andmigrate content when it decides to. Alternatively, a master server, ormonitor server, may be “others-aware” and may decide to migrate contentfrom other servers (it may also be “self-aware”). The monitoring may bevia NIC cards/ports. Any server, e.g. a content server, may be able tomonitor groups of servers of interest (and hence be a monitor server).

[0413] Self-aware and others-aware functionality may be used to migratedata onto servers on a network and/or to look for other problems andcompensate automatically for them. For example, an “impaired” server maybe impaired because it is approaching capacity and will struggle toserve out further resources, or because it has a fault, or because thetelecoms links to it are faulty, or themselves struggling with capacity.Whatever the reason for the impairment to the ability of a server toserve out in the future resources in response to a request for resourcesavailable on the server, some embodiments of the invention allow these“impaired” or “missing” resources to be made available from other, lessimpaired, servers, so as to maintain the capability of the network as awhole to serve out the resource in question. They system may monitor forfailures, or high level usage, or both. Data logging may be performed toensure usage levels are within acceptable/usual bounds.

[0414] An example of failure monitoring is: a managementstation/director server monitors connections to a collection of serversand usage of the content on those servers (this may be on a per portbasis, for example when running multiple instances of the same serverapplication (e.g. web serving/video streaming)). When a given server orservers fails, the management station ensures that new servers arebrought into play by spawning the appropriate application processes onnew servers to cope with the loss and content is replicated to the newservers from its source. In order to do this, the management station ordirector server monitors each of the compute elements delivering a giventype of content (e.g. web serving, video serving, FTP serving) andretrieves utilisation information from each of the servers, whenconnections to a server fail the management station/director serverinstigates a replication of the contents from its original source (whichis assumed to be replicated elsewhere) on to the new server and startsappropriate application services on that server to enable it to servethe new content. The director then updates appropriate load balancingtechnology or routing tables in use to allow that new server resource tobe utilised (e.g. hardware load balancing switch) and the failed serveris removed from the configuration until such time as it s repaired andcan be brought into play.

[0415] An example of high level usage monitoring is:

[0416] A management station/director server monitors connections to acollection of serves and usage of the content on those serves (this maybe on a per port basis, for example when running multiple instances ofthe same server application (e.g. web serving/video streaming). Whencontent becomes “busy” on a given server, or servers, the managementstation ensures that new servers are brought into play by spawning theappropriate application processes on new servers to cope with the demandand content is replicated to the new servers from its source.

[0417] The management station or director monitors each of the serversdelivering a given type of content (e.g. web serving, video serving, FTPserving) and retrieves utilisation information from each of the servers.When connections to a server increase over a given threshold themanagement station/director instigates a replication of the content ontothe new server and starts appropriate application services on thatserver to enable it to serve the new content. The director then updatesappropriate load balancing technology or routing tables in use to allowthat new server resource to be utilised (e.g. hardware load balancingswitch).

[0418] It will be appreciated that a demand director/monitor server, orother processor, can evaluate whether a current level of servers and acurrent distribution of resources on those servers is capable of meetingexpected reasonable levels of future demand, and if not to takeappropriate action to increase the chance of such future demand beingmet satisfactorily.

[0419] Although in principle the network benefits of aspects of theinvention can be obtained with two content servers (and a demanddirector or master server, with perhaps one of the content servers beinga demand director and/or master server as well), there will be manytimes when the benefits show more clearly when there are 3, 4, 5, 6, 7,8, 9, 10, 20, or more content servers. There may be of the order of atleast half a dozen content servers. By having a large number of contentservers (e.g. 6 or more), or a very large number of content servers(e.g. 10-15 or more), it is possible to have significantly differentcontent on different servers, possibly even sub classes of content ofthe same general kind on different servers. (for example, it may bepossible to have action movies on one server, comedy on another, sciencefiction on another, romantic on another, drama on another, etc.)

[0420] It will be appreciated that a significant advantage of manyembodiments of the invention is that the level of service available on anetwork accurately reflects consumption of the resources. We believethat it may not be desirable to replicate data and application softwareservices endlessly such that capacity is only ever over-provided. Theamount of application serving that the collection of resource serverscan provide at any one time may, in some embodiments, accurately reflectconsumption of those resources by users. There may be a “low water mark”that ensures that there is never complete cessation of applicationserving in the event of consumers appearing, possibly suddenlyappearing, not to want to resource anymore. It may well be undesirableto make the user wait until a resource can be copied and an applicationserver brought up to service a request for that resource. It maytherefore be desirable always to have at least one copy of allpotentially available resources available for serving, or at least onecopy of all potentially available resources present in the memory of aresource server (or accessible to the resource server), and appropriateapplication software for serving out any specific resource.

[0421]FIG. 29 shows a further example of a Video Farm 2910. Video Farm2910 comprising video servers 2912, 2914, 2916, 2918, 2920, 2922connected in a local area network 2924, and FIG. 29 also shows a user2926 connected to the network 2924 (possibly via the internet). Eachvideo server has a number of video movies on it, say about 100 to 500movies on each, with each movie being of about 1½ hours-2 hoursdirection. FIG. 29 shows schematically each video server with 3 movies.In the case of video server 2912 they are movie V1, movie V2, and movieV3. In the case of video server 2914 they are movie V4, movie V5, andanother copy of movie V1. It will be seen that some movies are presenton more than one video server. Furthermore, sometimes more than one copyof a movie is present in the same video server (see video 2920 which hastwo copies of movie V7).

[0422] As shown in FIG. 20, each video server has a central processor3010, a memory 3012 containing the video movies, a number of videostreaming output ports 3014, 3016, 3018 or connections, a monitoringinput port or connection 3020, and a control signal output port orconnection 3022. Control software 3024 resides on the processor 3010 ofeach video server.

[0423] The control software 3024 makes each server capable of being“self-aware” and of being “others aware”, in the sense of being able todetermine the performance abilities and/or characteristics of each videoserver in the farm 2910.

[0424] This enables the video server to self manage and execute remedialactions based upon their visibility of video content usage on thenetwork, and upon the ability of each video server to deliver videocontent. It also enables an individual server to contribute to managingthe performance as a whole. The video farm 2910 is able to distributevideo content dynamically, in response to changing conditions, over thevideo servers of the farm, and to bring up a new serving processes whenit is determined appropriate to do so. For example, if one video serverfailed, e.g. server 2916, the video farm can create extra copies ofthose videos that were capable of being served out from server 2916 onthe other servers, so that the overall capacity of the farm to serve outvideos stored upon (or accessed via) a faulty server is notsignificantly changed. FIG. 29 also illustrates fault tolerance forvideo files: for each server having certain videos, or video items,stored on it there is another copy of each of its video items stored onat least one other server. This means that if one server is faulty, orthe telecommunications lines to it are faulty, its content is stillaccessible from elsewhere on the farm, available to be copied/broughtinto service.

[0425] In the video farm 2910 one of the video servers, say server 2912,takes the role of master video content servability monitor and is awareof its own operational conditions and parameters and has the operationalconditions and parameters of the other servers 2914 to 2922 communicatedto it via its port 3020.

[0426] If for any reason the current master video server, server 2912,is unable to perform its role properly (e.g. it develops a fault or itstelecommunication links to the rest of the farm become impaired) anotherof the video servers can take over as the master video server.

[0427]FIG. 31 illustrates one of the software process that is happeningon the processor 3010 of the master video server, e.g. server 2912.

[0428] There are gating thresholds programmed in for performanceparameters, possibly by a system manager (person) and generally they arealterable/reprogramable (a generic fixed threshold would not be able toadapt to the usage conditions experienced). In FIG. 31 the performanceparameter is to the level of usage of each video item (e.g. video movie)capable of being served out by the video farm. Usage levels for videoitems are checked in parallel, rather than sequentially, as illustrated.

[0429] The master video processor determines how many video items ofeach specific video item is being served out (e.g. how many video V1 sare being streamed out, how many video V2 s are being played, how manyV3 s are being played etc). The number of video items being playedcurrently is checked, for each video item (movie) against an evaluatedknown, total capacity of the farm to serve out each specific video item.It is desired to have the level of resources in the farm such that it ispossible to serve out another specified number of each video item, inaddition to those currently being served out. This additional, reservecapacity, number of servable video items may be the same for each videoitem (i.e. the farm is capable of serving out 3 more V1 s, 3 more V2 s,3 more V3 s etc), or it may be different for at least one of theservable video items (e.g. 5 more V1 s in reserve, 2 more V2 s, one moreV3, etc). It may be desirable to have a higher reserve capacity to serveout a popular video movie than a relatively unpopular movie. For examplea newly released movie may be in more demand by users and it may beappropriate to have more reserve capacity to serve out that movie thanan older “classic” movie (such as Gone with the Wind). More users arelikely to want to access a new release in a short time.

[0430] Thus upon checking the usage of video, referred 3110 in FIG. 31,the processor 3010 compares the actual number of videos of each specifictitle being served (reference 3310 in FIG. 33) out with the potentialcapable of currently being served out (reference 3312) and establishes areserve capacity 3314 to serve out video V1 in the short-term future.This reserve capacity 3314 is compared with a maximum threshold level,3316, and with a minimum threshold level 3318 and the capacity of thefarm to serve out extra additional copies of V1 in the future isincreased, reference 3320, or decreased, reference 3322, depending uponwhether the minimum or maximum threshold is met or exceeded.

[0431] The capability of the farm 2910 to serve out a specific video V1can be increased by starting up appropriate video serving applicationsoftware on a video server that already has the specific video V1, or bycreating extra copies of it on the servers 2912 to 2922, and/or makingavailable greater telecommunications capacity for V1, e.g. by opening upvideo serving applications on ports (parts of the network address space)of the video server that were previously used for something else (e.g.voice telecomms or text communications). Similarly, capacity to serveout V1 can be reduced, freeing up capacity to serve out other videos, byshutting down software applications that access V1 in the memory of oneor more servers and/or by overwriting or deleting V1 in the memory ofone or more servers. It is probably best as a first measure simply todisable the ability of the server to serve out V1 (still retaining V1 inmemory of the server, e.g. in disc storage accessible by the server).This is easier to reverse in the future and often it is the processingpower of a server's CPU, or the telecoms availability at its connectingports, that restricts serving capacity rather than absolute lack ofmemory accessible by the server for extra copies of popular videos.

[0432]FIG. 32 schematically illustrates software on the processor 3010checking other parameters which can effect the overall ability of thefarm to serve out content. Boxes 3210, 3212, 3214 show the processorchecking a number of different parameters (in this case 3) for each ofthe servers in the network (in this case 6). The parameters are checkedin separate threads of execution (i.e. in parallel). Box 3216 shows acomparison of each parameter with one or more respective thresholds(e.g. parameter/with maximum threshold 1 and minimum threshold 1, andparameter 2 with maximum threshold 2 and minimum threshold 2). Box 3218shows the processor sending out control signals in response to thresholdconditions being true. The actions initiated by the control signals arepreprogrammed, typically by a system administrator (person), and cantypically be amended and new different actions, or new differentthreshold conditions can typically be input (again typically by asystems administrator).

[0433]FIG. 34 illustrates one parameter being monitored: bandwidthavailable for new users at a specific video server, say server 2922. Themaster server 3022 polls each of the other servers 2914-2918 in thenetwork to ask them how much bandwidth they are using. Each server runsa routine on its external network communications NIC card which monitorsan appropriate parameter and reports to the master server. Thusbandwidth being used is established for each server, referenced 3410.The potential available bandwidth to each server is known to the masterserver (referenced 3412), or to each server itself. This enables abandwidth free for future use FIG. 3414, to be established. This iscompared with an upper threshold 3416 and if it is above that (too muchbandwidth available 3418) then remedial action is taken. In this casebox 3420 illustrates the allocation to a video server (e.g. server 2922)which is adjudged to have too much free bandwidth of additional requeststo serve out new videos. That is to say, in a load balancing routinecontrolled by the master server 2912 requests to be served a video itemcan be allocated to whichever video server is adjudged to havesufficient, or best, telecommunication availability. This can at leastbe one of the factors in deciding to which video server a request for avideo is sent (assuming more than one server has the video available forserving).

[0434]FIG. 34 also shows a comparison 3422 of the free bandwidthavailable for use, for each server, with a lower threshold. If it isestablished that there is too little free bandwidth, 3424, then remedialaction is taken. This action could be, as shown in 3426, the decisionnot to direct new requests for videos to be served out to the particularserver that is getting close to its bandwidth capacity.

[0435] The actions 3470 and 3426 need not be as described. For example,a video actually being served out of the server that is adjudged to betoo busy (too great a strain on telecommunications links) may be startedup on another server, and (optionally) shut down on the busy server withan arrangement so that a user currently receiving the video from thebusy server does not notice the transfer of the source of the video tothe less busy server.

[0436] The thresholds may be adaptive, in the sense that a threshold fora specific server may go up or down depending upon what is happeningelsewhere in the network. For example, whilst it may normally beundesirable to start up more videos on a server that is using 80% of itstelecomms bandwidth, the master server may not have any choice if thatserver is the only server to have a copy of the requested videoavailable for serving to a new user.

[0437] As a further example, the network may have a control databasethat maintains network-wide global, serving state details for eachserver. This may be held in the master server, or elsewhere.

[0438] A guide to what might be appropriate code is:

EXAMPLE 1

[0439] Database (vf0, vf, vf, vf) {

[0440] query (“select * from showing”)}

[0441] (.inactive<3): ‘cool’+titleID (.inactive>3): ‘heat’+titleID

[0442] } every 2 seconds

EXAMPLE 2

[0443] exec (‘bandwidth vf2’) {

[0444] <1024 k: ‘bringup vf3’

[0445] >2048 k: ‘mover vf2’

[0446] } every 10 seconds

[0447] }

[0448] The wrapper whole database ( . . . ) { } specifies a database torun queries against, within that, queries are of the ‘exec’ or ‘query’form. The fist example here specifies that is a title that is currentlyshowing has more than three inactive connections, it should reduce thatserving capacity for that title by calling an external process called‘cool’ with an argument specifying which title to cool. Conversely, ifthere are less than three inactive connections for a given title, thenmore serving processes for that title should be started up, by callingan external process called ‘heat’ with an argument specifying whichtitle needs more serving capacity from the farm. In both cases, cool andheat then run queries against serving capacity of the farm and makejudgements based on appropriate serving loads on resource servers todetermine where those new serving processes are started up.

[0449] The case of example 1 illustrates the desire that a given videotitle served should never have too many active processes able to serveit: hence if more than three active connections, reduce the ability toserve that title—in this case it is assumed that this would be theresult of running the external process ‘cool’ with the title to cool asa specified argument (i.e. title 12 would be ‘cooled’).

[0450] The second case illustrates the desire to check the availablebandwidth from a video server called vf2—the separate code called“bandwidth” can be run up on either the server vf2 or upon a remoteserver connected to vf2 via a network. When run upon vf2 “bandwidth”returns the data transfer rates from vf2, typically obtained from thenetwork card of vf2. If vf2's transfer rate is above an upper thresholdvalue, for example 2 MB/sec, another server is brought into use in orderto reduce the load on vf2. If vf2's transfer rate is below a lowerthreshold, for example 1 MB/sec, it will typically be allocated morecontent to serve as it is not fully utilising its data transfercapacity.

[0451] When run upon a remote server “bandwidth” samples the datatransfer rate that is available from vf2. In this case if the sampledavailable transfer rate is below a threshold value, for example 1MB/sec, vf2 is using a significant faction of its available datatransfer capacity and therefore another serve is brought in. Conversely,if the sampled available transfer rate is above a threshold value, forexample 2 MB/sec this indicates a significant fraction of vf2's datatransfer capacity is unused. Therefore vf2 can be allocated more contentto serve.

[0452] In either case, it is assumed that the external processes “bringup” or “move” will cause those events to occur.

[0453] All of the items within the database ( ) { } block are run inseparate threads, i.e. not sequentially—so in this manner as soon as thecondition become true remedial action is taken. The condition can alsobe set for various times. (see the ‘every N seconds’). This ensures thatthe monitoring process does not swamp the CPU upon which it is beingexecuted and also that if measuring statistics, they are measured overan appropriate time period—i.e. in the case of network statistics it isnot burst capacity that is being measured.

[0454] It will be appreciated that although FIGS. 33 and 34 usedcapacity was monitored and unused capacity evaluated from that, it maybe possible to monitor unused capacity directly.

[0455] The master server is typically aware of its own activities as avideo server. If it is not actually a video server then clearly it neednot know of its own serving activities/capabilities.

[0456] There are at least three things which can impair the ability of avideo server to serve out a video to a user. Firstly, thetelecommunication capability from the server's output port or connectionto the user; secondly, the internal telecommunication within the serverfrom the server's memory to its output port or connection (the video hasto get from memory to I/O port); and thirdly the CPU performance (theCPU has to control, manage, and perhaps format or encode the datastream,and call it from memory). All three of these can be parameters to bemonitored. We have already discussed the first. It is possible tomonitor the I/O streaming performance of the disc substream (disc to I/Oport)—the storage I/O performance. It is also possible to monitor CPUperformance (e.g. how many of its clock cycles per second are actuallybeing used).

[0457] By “memory” of the server is meant fast access chip memory, disc(non-volatile) memory inside the server, and memory attached to theserver, but not necessarily physically in its housing.

[0458] It will be appreciated that each video server could run its owndiagnostic on itself and communicate the results to the master server.Alternatively the master server could interrogate each server for theirself-performed diagnostic result. Alternatively the master server couldperform the diagnostic routines on the other servers.

[0459] When a server is completely cut off from the remainder of thenetwork, or completely. “dead” it cannot communicate anything to themaster server. The absence of information/an appropriate response to aquery can itself serve as information to the master server to be actedupon.

[0460] Performance/capacity information may be obtained for each videoitem: each video movie may be evaluated as a separate thread of enquiry.

[0461] It will be appreciated that a demand director/load balancingserver could take into account not only the question of whether aparticular video server has a particular video content upon it, but alsowhether its telecommunications, CPU, and memory access were capable ofserving out a requested video effectively, and could allocate requestswith this capacity in mind. Furthermore, if it seemed appropriate tore-distribute video content over the video servers in the network thiscould be done automatically. For example, if a particularly busy videoserver had one copy of movie 101, and only one other quieter videoserver had a copy of movie 101, the master server could cause movie 101to be copied as a precaution, e.g. from the “quieter” server, to anotherserver so that there was an increased spare capacity to serve out movie101.

[0462] Similarly, if a specific server developed a fault and wasinoperative, or could not be communicated with (fault intelecommunications) then the master server could take that into accountwhilst dynamically controlling the distribution of video content overthe receiving servers and/or whilst allocating requests for videos to beserved out to specific ones of the remaining video servers.

[0463] The master video server 2912 checks parameters beyond usagelevels of specific video movies.

[0464] It is desirable to load balance telecommunications over the videofarm so as to avoid bottlenecks in data transfer/video streaming.

[0465] Other parameters which could be monitored, and used to controloverall network performance—affecting things include:

[0466] Memory usage

[0467] Latency (response time to “pings”)

[0468] CPU utilisation

[0469] Average I/O rate per second

[0470] Other performance indicative statistics.

[0471] The above could be per server (and usually will be), but couldalso be evaluated for the network as a whole. For example, it may bepossible to determine that nothing is wrong with any server but thatnevertheless the network is struggling to meet demand and that moreservers and/or better telecoms and/or better CPU's are needed. Theremedial action may be automatic (e.g. co-opting in another server), orit may comprise the automatic generation of a report or alert to beacted upon by a human.

[0472] The response to monitored parameters meeting pre-programmedconditions could be based upon existing demand, or could be policy-basedto take into account projected future demand. For example, greater freereserve bandwidth may be required at a time of day when it is knownpeople like to watch video movies (e.g. 8.00 pm) and the acceptablethresholds may be adjusted, automatically or manually (e.g. by alteringa program) to allow for that. The software allows programmablespecification of network and serving conditions that require remedialaction and the action(s) to be taken based upon those conditionsbecoming true.

[0473] The memory of a video, or resource, server typically includesnon-volatile disc memory.

[0474] It will be appreciated that the inventions described can be usedwith each other, in any combination.

[0475] It will be appreciated that in some embodiments the inventionuses a local area network, rather than a wide area network, and someembodiments involve rich media (e.g. video) farms of servers (very localservers—local to each other, often in the same room). For WANarrangements, especially those involving the internet, and possiblyinvolving thousands of miles of telecoms cables, the speed of light (foroptical cables) can still not be fast enough to avoid issues associatedwith large distances between client and server, especially for timedependent consumable resources, such as streamed video files.

[0476] Many embodiments of the invention allow a resource (e.g. video)to be streamed out/delivered from a server using a particularapplication software on that server to cause the data representing thevideo movie to be streamed out properly. The same video may be servableout of a server using different application software, e.g. capable ofhandling/formatting the video data differently for different clientrequests. For example Real Player, Windows Media Play, and Quick Time,are three known, and different video serving application software whichcan operate on the same video data/file (or different video data (file)records) to serve out a video to a user/client in different protocols orformats.

[0477] A particular server may have the video file, or other data recordof the video, in its memory, or in local attached memory. Said servermay have first application software capable of serving out the videofile present in local memory in the server, or in a server farm to whichsaid server belongs, or it may not.

[0478] The first application software may be adapted to serve out thevideo file in a first way to comply with a first protocol. The firstapplication software, when presented on the said server, may beinstalled on the server, or it may not actually be installed: it couldsimply creatable by said server using “first application installation”software that is installed on the server. Or, the application softwaremay need to be telecommunicated to said server (or the first applicationinstallation software telecommunicated) to enable said server to havethe capability of serving out the video file.

[0479] The first application software may be running on the said server,or it may be installed but not running: it may need to be brought up toa running condition. The first application software even when running onthe server may be engaged in actually serving out the video file or itmay not: it still may be capable of serving out a further video wheninstructed to do so.

[0480] Thus, to cause said server to serve out said video a migratorcontroller may or may not have to migrate the video file itself to theserver, depending upon whether the server already has a video fileavailable or use in serving out the video. The first applicationsoftware, necessary to serve out the video in the first way, may need tobe migrated to said server, or it may not, depending upon whether italready exists and whether, this currently fully utilised in serving outvideo.

[0481] The first application software may need to be installed if italready exists on the server, or it may not, depending upon whetherthere is already installed first application software free for use (nototherwise occupied). Or first application installation software may ormay not need to be migrated to the said server, depending upon whetherit already exists on the server in a useable form.

[0482] An instruction to said first server to install the firstapplication software may need to be transmitted to said server.

[0483] An instruction to run installed first application software mayneed to be transmitted to the said server.

[0484] Similar points apply to second, and further, application softwarecapable of serving out the video file in second, and further, ways thatcomply with second, and subsequent protocols.

[0485] Which of a plurality of video-serving application software it isnecessary to have running on the server to satisfy a request for thevideo depends upon the format of the video requested by the client.

[0486] Just as different data software/software may or may not need tobe transmitted to a server to enable it to serve out an additional videoat any particular time, when a specific server stops serving out a videoin a particular format it may be appropriate to bring down the runningof a specific video serving application software in order to reducedemand on the processing unit of the server. This may involve leavingthe application software installed, but not running, or de-installingit. Usually the application-installation software would be left on theserver, but it might also be de-installed. Usually the video file wouldbe left on the server, but it also might be de-installed/removed frommemory there.

[0487] Many embodiments of the invention determine whether it isnecessary to transmit to a selected server that is to serve out aspecific video in response to a specific demand for the video by aclient the particular kind of video serving application softwarenecessary to serve the video out in a way that will meet the demandedformat, and will migrate/transmit to the selected server the minimumdata/software necessary for it to achieve the serving out of therequested video into the requested format (i.e. they will notautomatically transmit to the server everything it might conceivablyneed (application software and video file), just what it does notalready have free for use, or that it cannot create itself). Thistailoring of the migrated software and data to the specific needs(present or future) of the server reduces the utilisation of bandwidthin the migration process, leaving more bandwidth free for the actualsatisfying of client requests for videos.

[0488] Also, in a system where the resources that are servable out areof different kinds (e.g. different kinds of video formats, and/or webpages, and/or audio only media, and/or other rich media), there may beother serving out application software necessary to serve out the actualdata representative of those different kinds of resources.

[0489] In determining which servers are capable of satisfying aparticular demand a demand server has to establish what applicationsoftware it is necessary to have running on the chosen resource server,and that the selected resource server not only has access to the datacontact of the resource to the served out but also to the appropriateserving-out application software necessary to serve the data out in therequired way.

[0490] It will be appreciated that a signal from a demand director touse video serving application software that is already running on avideo server to serve out a particular video title, and a signal tobring up to a running condition installed video serving applicationsoftware, or to use application-installing software to install and run avideo serving application, has fewer bits in it than actuallytransmitting a video serving application-installing software to aserver, which in turn has fewer bits than actually transmitting videoserving application software itself to the server, which in turn hasfewer bits than transmitting a video file data record itself.

[0491] When moving data around a farm, or local area network, or indeedaround a wide area network, many embodiments of the invention assess theneed to move video data records, e.g. files, (for example), or whetherit is possible to move something that has fewer bits. For examplemigrating or copying a particular video-serving application softwareprogram to a specific server that already has video data ready forserving may enable that specific server to serve out an additional copyof that video. This may consume less network resource thanautomatically, without consideration, migrating the desired video fileand the necessary application software to serve it out in a specificformat.

[0492] Similarly, migrating or copying video-serving applicationinstallation software, a condensed packaged software program which canbe used by the recipient server to create the required format/protocolof video serving software, can reduce the network resources consumed inenabling a new server to have the capacity to run video servingapplication software of the desired format/protocol. This may be done inadvance, before there is an actual demand for a video (or other richmedia or other resource) to be served out, so as to maintain capacity torespond to a future request to serve out video in that format/protocol.For example, if a particular video server has a plurality of unusedvideo serving application software of a first format/protocol running orinstalled, but no unused video serving application software of a second,different, kind of format/protocol, running or installed it may bedesirable to have that server run or install an appropriate softwareprogram of the second format in place of one of the application softwareprograms of the first format (so that there is reserve capacity of videoserving application software of both formats on the video server).

[0493] The second format of video serving application software may becopied, installed or brought up running from within the server inquestion, or it may be migrated to the server in question from anotherserver. Distributing ready-for-use, unallocated, running or installed(or installation) video serving application software over a farm, orlocal area network, or of video servers, without necessarily migratingvideo files themselves, in order to be ready to serve out videos fromthe servers in a variety of formats/protocols is what is achieved bysome embodiments of the invention.

1. A method of maintaining availability of requested network resourcesof a network of servers each having associated network-servableresources of a specific kind, the network including resource data andresource-serving application software adapted to serve out said resourcedata, the method comprising dynamically distributing capacity to serveout servable resources between said resource servers dependent upondemand for said resources, thereby varying capability of said network asa whole to serve out a particular resource dependent upon the level ofdemand for said particular resource, and wherein said distributing ofcapacity to serve out servable resources comprises distributing at leastone of: (i) resource-serving application software; (ii) installationsoftware adapted to install resource-serving application software; thedistribution being between said resources without necessarily moving theresource data itself between servers.
 2. A method according to claim 1wherein an additional particular resource, including both resource dataand resource-serving application software, is created on said network soas to increase capacity of said network to serve out said particularresource.
 3. A method according to claim 2 wherein resource-servingapplication software of a specific kind is copied from a first resourceserver to a second resource server, thereby increasing the capacity ofsaid network to serve out resource data in a format or protocolassociated with said specific kind of resource-serving applicationprotocol.
 4. A method according to claim 1 wherein said resource servershave port addresses and a particular resource servable from a first portaddress is made available for serving from a second port address byallocating appropriate resource-serving application software to saidsecond port address.
 5. A method according to claim 4 wherein said firstand second port addresses are associated with the same server.
 6. Amethod according to claim 4 wherein said first and second port addressesare associated with different resource servers.
 7. A method according toclaim 1 which comprises automatically dynamically expanding capacity ofa video serving network to serve out a specific video, comprising saidnetwork servable resource, by either of (i) copying said specific videoto another said resource server, or (ii) by having videos servable outfrom port addresses of said servers and by making said specific videoavailable for serving out from an increased number of port addresses, orby making said specific video available for serving out from a portaddress with an increased capacity to serve out said specific video. 8.A method according to claim 3 further comprising at a different timefreeing capacity in said network to serve out other said resources byreducing serving capacity of a different resource.
 9. A method accordingto claim 3 comprising distributing said resources, or at least saidresource data, between said resource servers in a homogenous manner sothat each resource server has substantially the same resources, orresource data of said specific kind.
 10. A method according to claim 3comprising asymmetrically, non-homogeneously, distributing saidresources of said specific kind so that not all resource servers havingresources of said specific kind have the same resources of said specifickind available for serving.
 11. A method according to claim 1 wherein anadditional resource server, not part of said network at a first time,joins said network in order to increase capacity of said network toserve out said particular resource.
 12. A method according to claim 11wherein said additional resource server has resource data comprising atleast one of said particular resource and resource-serving applicationsoftware adapted to serve out said resource data copied to it to enablesaid additional resource server to be capable of serving out saidparticular resource.
 13. A method of data storage management of data ina network comprising the steps of:— (i) monitoring usage of a servableresource; (ii) determining if said usage of said resource has increasedor decreased; performing at least one of steps (iiia) and (iiib),wherein step (iiia) includes introducing at least one of an additionalresource server to said network and starting up a resource-servingapplication on a resource server if said usage has increased; and step(iiib) includes removing at least one of said resource from a resourceserver and shutting down a resource-serving application on a resourceserver if said usage has decreased.
 14. A method according to claim 13comprising maintaining and updating a database including details ofwhich resource servers have which particular resources thereon.
 15. Amethod according to claim 13 comprising maintaining and updating adatabase including details of which resource servers have: whichresource-serving application software running on them, or installed onthem; or installation software adapted to install which resource-servingsoftware.
 16. A method of data management comprising the steps of: (a)monitoring at least one of traffic on at least one data content serveron a network and software application response time for an applicationsoftware running on at least one data content server on a network; and(b) starting up or shutting down an appropriate data serving applicationautomatically upon said server or upon a further server on the networkin response to at least one of network traffic and application responsetime.
 17. A method according to claim 16 comprising copying at leastpart of the data content of the data content server to said furtherserver.
 18. A method according to claim 16 comprising copying said dataservers application software to said further server.
 19. A methodaccording to claim 16 comprising updating routing/load balancing tablesassociated with said data content servers.
 20. A method according toclaim 16 comprising adding a further server to a server network anddirecting a portion of the network traffic to said further server.
 21. Amethod according to claim 16 comprising (i) providing the server as aserver application upon the data content server; or (ii) providing theserver as a further data content server.
 22. A method according to claim16 comprising copying at least part of the data content, or saiddata-serving application, from said data content server.
 23. A methodaccording to claim 16 comprising copying at least part of the datacontent from a source, or said data-serving application that is not saiddata content server.
 24. A method according to claim 16 comprisingexecuting step (b) of the method in response to a change in networktraffic due to any of the following: application server failure,application response time, application server overload, insufficientservers present upon a server network based upon a statistical model.25. A method according to claim 1 wherein said resources or said datacontent comprise one of: rich media; video; audio.
 26. A networkcomprising resource servers each having a deliverable resource of aspecific kind available for serving out, and a resource manager adaptedto receive a demand indicator input indicative of demand for aparticular one of said deliverable resources of said specific kind andto output a resource-varying output adapted to vary capability of saidnetwork as a whole to serve out said particular one resource, saidresource-serving output being adapted to vary the level available foruse of resource-serving application software running, installed, orinstallable from application-installation software on said resourceservers of said network.
 27. A network according to claim 26 whereinsaid resource-varying output comprises a resource migration signal forcausing either: (i) said particular one resource to migrate or be copiedfrom one resource server, or (ii) said resource-serving applicationsoftware, or installation software for said resource serving applicationsoftware, to migrate or be copied from one server to another.
 28. Anetwork according to claim 26 wherein said resource-varying output isadapted to cause copying of said particular one resource, or of saidapplication software, or of said installation software, so as to causesaid particular one resource to be at least one of present and servableout on said one server and also on said another server.
 29. A networkaccording to claim 28 wherein said resource-varying output is adapted toincrease capacity of said network as a whole to serve out saidparticular one resource.
 30. A network according to claim 26 whereinsaid resource servers have port addresses and wherein said particularone resource is available for serving from one port address of a saidserver and wherein said resource varying output causes a second portaddress of a said server to have said particular resource available forserving.
 31. A network according to claim 30 wherein said second portaddress is a port address of the same resource server that has saidfirst port address.
 32. A network according to claim 30 wherein saidsecond port address is provided on a different said resource server tothat said resource server which has said first port address.
 33. Anetwork according to claim 26 wherein said resource-varying output isadapted to reduce serving capacity of said network as a whole to serveout a selected resource.
 34. A network according to claim 26 whereinsaid resource-varying output causes said resources of said specific kindto be distributed homogeneously over said resource servers that are insaid network.
 35. A network according to claim 26 wherein saidresource-varying output causes said resources of said specific kind tobe distributed asymmetrically, non-homogeneously, over said resourceservers so that at least one of said resource servers has differentresources of said specific kind available for serving out.
 36. A networkaccording to claim 26 wherein said resource-varying output is adapted tocause an additional server, external to said network, to be contactedand joined with said network.
 37. A network according to claim 36wherein said resource-varying output also causes a selected resource, orresource-serving application software, or installation software forresource serving application software, present on said network to becopied to said additional server and made available for use on saidadditional server.
 38. A network according to claim 26 wherein saidresource manager comprises a said resource server.
 39. A networkaccording to claim 38 wherein each said resource server is capable ofacting as said resource manager.
 40. A network comprising a plurality ofresource servers adapted to serve out servable resources of a specifickind; a usage monitor; and a resource manager; said usage monitor beingadapted to monitor usage of said servable resources and to determine ifa usage level of a particular said resource has changed significantlyand to communicate such changes in usage level to said resource manager,said resource manager being adapted to do at least one of (a) introducean additional server to said network, (b) start up a resource servingapplication on a networked resource server if usage of said servableresources has increased significantly, (c) remove said specific resourcefrom a networked resource server and (d) shut down a resource-servingapplication on a networked resource server if said usage of saidservable resources has decreased.
 41. A resource management serveradapted for use with a plurality of resource servers having resources ofthe same particular kind available for serving out, said resourcemanagement server being adapted to evaluate demand for a particular oneof said resources of said specific kind, in use, in order to varycapacity of said network to serve out said particular one resource inresponse to changes in demand for said particular one resource, andwherein said resource management server is adapted to alter the numberof resource-serving applications of a specific kind adapted to serve outresource in a specific particular format or protocol that is running,installed, or in installation software format, available on saidresource servers as a whole and available for future use.
 42. A serveraccording to claim 41 capable of causing said particular one resource,or application software, to be copied from a first server in saidnetwork to a second server in said network so as to increase capacity ofsaid network to serve out said particular one resource.
 43. A serveraccording to claim 41 adapted to cause initiation of serving out of saidparticular one resource from a port address of one of said resourceservers by bringing up running appropriate resource-serving applicationsoftware, said port address being either (i) on a resource server thatis already serving out said particular one resource from a differentport address, or (ii) on a resource server that was not previouslyserving out said particular one resource.
 44. A server according toclaim 41 having resource of said specific kind and which comprises aresource server capable of serving out resource of said specific kind.45. A content management server adapted for use with a content servernetwork, said content management server comprising a servable contentmonitor adapted to monitor levels of usage of servable content of aspecific kind, and a content availability manager adapted to change theavailability of specific servable content depending upon demand for saidspecific servable content; said content management server being adaptedto perform at least one of (a) the function of an additional resourceserver to a network, (b) starting up a content serving application on acontent server if levels of usage of a particular content have increasedsignificantly, (c) removing content from a networked content server, and(d) shutting down a content serving application on a content server iflevels of usage of a particular content have decreased significantly.46. A content management server according to claim 45 which is itself acontent server capable of serving out content of said specific kind. 47.A resource management server adapted for use with a plurality ofnetworked resource servers having resources of a common particular kindavailable for serving out, said resource management server comprising ademand evaluator adapted to evaluate demand for a particular one of saidservable out resources of said specific kind, and a capacity modifieradapted to modify capacity of said network to serve out said particularone resource, said capacity modifier being arranged to be responsive toevaluated demand signals from said demand evaluator and being adapted todistribute resource-serving application software over servers of saidnetwork so as to maintain unused available capacity to serve outresource.
 48. A video server for use in a video farm or a network ofvideo servers, the video server being arranged for having videosavailable for serving out, said video servers comprising a videomigration manager adapted to receive video demand-indicative signalsindicative of the level of demand on said farm or network for saidvideos available for serving, the video manager being arranged forcausing activation of video serving application software on a videoserver which has a copy of said particular video available, therebymaking said particular video available for serving from said videoserver, and wherein said video migration manager is adapted to operateautomatically in response to demand for said videos without humanintervention so as to dynamically distribute video serving capabilitiesover said video servers of said farm or network.
 49. A video server foruse in a video farm or a network of video servers, the video serverhaving videos available for serving out, said video server comprising avideo migration manager adapted to receive video demand-indicativesignals indicative of the level of demand on said farm or network forsaid videos available for serving, the video manager being arranged forcausing the copying of a particular video for which said demand issufficiently high from a first video server where it is available forserving to a second, different, video server and to make said particularvideo available for serving from said second video server so as toincrease the capacity of said farm or network to serve out saidparticular video, and wherein said video migration manager is adapted tobe responsive to demand for said videos to operate automatically withouthuman intervention so as to dynamically distribute video servingcapabilities over said video servers of said farm or network.
 50. Avideo server for use in a video farm or a network of video servers, thevideo server being arranged to have videos available for serving out,said video server comprising a video migration manager adapted toreceive video demand-indicative signals indicative of the level ofdemand on said farm or network for said videos available for serving,the video manager being arranged for causing the serving out of aparticular video for which said demand is sufficiently high from anincreased number of port addresses of a said video server where saidparticular video resides, thereby increasing capacity of said videoserver to serve out said particular video and wherein said videomigration manager is adapted to be responsive to demand for said videosto operate automatically without human intervention so as to dynamicallydistribute video serving capabilities over said video servers of saidfarm or network.
 51. A network including a plurality of the videoservers of claim
 50. 52. A video server for use with a video farm ornetwork of video servers each having videos available for serving out,said video server being capable of having videos available for servingout and comprising a video migration manager adapted to receive videodemand-indicative signals indicative of the level of demand on said farmor network for said videos available for serving, the video managerbeing arranged to cause activation of video serving application softwarefor a particular video, for which demand is sufficiently high, upon avideo server that has said particular video in memory, and wherein saidvideo migration manager is adapted to be responsive to demand for saidvideos to operate automatically without human intervention so as todynamically distribute video serving capabilities over said videoservers of said farm or network.
 53. A video server for use with a videofarm or network of video servers each having videos available forserving out, said video server being capable of having videos availablefor serving out and comprising a video migration manager adapted toreceive video demand-indicative signals indicative of the level ofdemand on said farm or network for said videos available for serving,the video manager being arranged to cause the copying of a particularvideo for which said demand is sufficiently high to be copied from afirst video server where it is available for serving to a second,different, video server and to make available for serving from saidsecond video server so as to increase the capacity of said farm ornetwork to serve out said particular video, and wherein said videomigration manager is adapted to be responsive to demand for said videosto operate automatically without human intervention so as to dynamicallydistribute video serving capabilities over said video servers of saidfarm or network.
 54. A video server for use with a video farm or networkof video servers each having videos available for serving out, saidvideo server being capable of having videos available for serving outand comprising a video migration manager adapted to receive videodemand-indicative signals indicative of the level of demand on said farmor network for said videos available for serving, said video managerbeing arranged to cause the serving out of a particular video for whichsaid demand is sufficiently high from an increased number of portaddresses of one of said video servers where said particular videoresides, thereby increasing capacity of said video server to serve outsaid particular video; and wherein said video migration manager isadapted to be responsive to demand for said videos to operateautomatically without human intervention so as to dynamically distributevideo serving capabilities over said video servers of said farm ornetwork.
 55. A network including a plurality of the video servers ofclaim
 54. 56. A video server according to claim 54, wherein said videomigration manager is also adapted to reduce capacity of said network orvideo server to serve out a particular video.
 57. A memory includingsoftware for controlling the distribution of network resources overresource servers of a network or of a video farm, the softwarecomprising a demand evaluation operative for establishing levels ofdemand for particular resources available on said network or farm, and aresource allocation operative to receive input from said demandevaluation operative and to cause, selectively, (i) resource-servingapplication software to be copied from one resource server of saidnetwork or farm to another resource server of said network or farmthereby to increase capacity of said network or farm to serve out saidresource; or (ii) a specific resource-serving application to be startedup and made servable out from at least one additional port address of aresource server that already has said specific resource in memory so asto increase capacity of said resource server to serve out said specificresource; or (iii) an additional server, not previously part of saidnetwork or farm, to be co-opted into said network or farm so as toincrease capacity to serve out resources; or (iv) cause any one of, orcombination of, (i), (ii) or (iii) to occur.
 58. The memory according toclaim 57 wherein said resource allocation operative is adapted to reducecapacity of said farm or network to serve out a particular resource. 59.A video farm or network of video servers each having videos availablefor serving out, at least one of said video servers comprising a videodemand manager adapted to receive video demand-indicative signalsindicative of the level of demand on said farm or network for saidvideos available for serving, the video manager being arranged to causeselectively, one of (i) deactivation of video serving applicationsoftware on a video server which has a copy of said particular videoavailable, thereby making said particular video unavailable for servingfrom said video server; or (ii) a particular video for which said demandis sufficiently low to be servable out from a decreased number of portaddresses of one of said video servers where said particular videoresides, thereby decreasing capacity of said video server to serve outsaid particular video; or (iii) deleting from memory of a video server avideo; or (iv) uninstalling or deleting a video serving application on aserver; or (v) any combination of (i), (ii), (iii) or (iv) to occur; andwherein said video demand manager is adapted to be responsive to demandfor said videos to operate automatically without human intervention soas to dynamically distribute video serving capabilities over said videoservers of said farm or network.
 60. A video server for use with a videofarm or network of video servers each having videos available forserving out, said video server being capable of having videos availablefor serving out and comprising a video demand manager adapted to receivevideo demand-indicative signals indicative of the level of demand onsaid network for said videos available for serving, the video managerbeing arranged to cause (i) deactivation of video serving applicationsoftware for a particular video, for which demand is sufficiently low,upon a video server that has said particular video in memory; or (ii)deletion from a memory of a video server of a particular video for whichsaid demand is sufficiently low so as to decrease the capacity of saidfarm or network to serve out said particular video; or (iii) aparticular video for which said demand is sufficiently low to beservable out from a decreased number of port addresses of one of saidvideo servers where said particular video resides, thereby decreasingcapacity of said video server to serve out said particular video; or(iv) uninstalling or deleting a video serving application on a server,or (v) to be able to cause, any combination of, (i), (ii), (iii) or (iv)to occur; and wherein said video demand manager is adapted to beresponsive to demand for said videos to operate automatically withouthuman intervention so as to dynamically distribute video servingcapabilities over said video servers of said farm or network.
 61. Amemory including software for controlling the distribution of networkresources over resource servers of a server farm or network, thesoftware comprising a demand evaluation operative for establishinglevels of demand for particular resources available on said farm ornetwork, and a resource allocation operative to receive input from saiddemand evaluation operative and to cause modification of capacity ofsaid farm or network to serve out particular resources, saidmodification comprising an increase in capacity or a decrease incapacity to serve out a particular resource, and said resourceallocation being operative for causing changes in the available unusedcapacity of applications running, installed, or installable, uponresource servers that are capable of being used to serve out each ofsaid particular resources, dependent upon demand for each saidparticular resource.
 62. Memory software according to claim 61 whereinsaid modification comprises an increase in capacity and said demandevaluation operative is adapted to cause: (i) resources to be copiedfrom one resource server of said farm or network to another resourceserver of said farm or network thereby to increase capacity of saidnetwork to serve out said resource; or (ii) cause a specific resource tobe started up and made servable out from at least one additional portaddress of a resource server that already has said specific resource inmemory so as to increase capacity of said resource server to serve outsaid specific resource; or (iii) cause an additional server, notpreviously part of said network, to be co-opted into said farm ornetwork so as to increase capacity to serve out resources; or (iv) causeany one of, or combination of, (i), (ii) or (iii) to occur.
 63. Thememory according to claim 61 wherein said resource allocation operativeis adapted to reduce capacity of said farm or network to serve out aparticular resource.
 64. A method of maintaining availability of a videofarm or local area network resources, the farm or local area includingnetworked video servers each having associated network-servable videos,the method comprising dynamically distributing videos between said videoservers of said farm or local area network dependent upon demand forsaid videos, thereby varying capability of said farm or local areanetwork as a whole to serve out a particular video dependent upon thelevel of demand for said particular video.
 65. A method of data storagemanagement of data in a video farm or local area network comprising thesteps of:— (i) monitoring usage of video files; (ii) determining if saidusage of said video files has increased or decreased; performing atleast one of steps (iiia) or (iiib), wherein step (iiia) includes atleast one of introducing an additional video server to said farm orlocal area network and starting up a video-serving application on avideo server if said usage has increased; and step (iiib) includes atleast one of removing one of said video files from a video server andshutting down a video-serving application on a video server if saidusage has decreased.
 66. A method of rich media data managementcomprising the steps of: (i) monitoring at least one of traffic on atleast one rich media data content server on a server farm or local areanetwork and software application response time for an applicationsoftware running on at least one rich media data content server on aserver farm or local area network; and (ii) automatically starting up orshutting down at least one of an appropriate rich media data servingapplication upon said server or upon a further server on the farm orlocal area network in response to farm or network traffic andapplication response time.
 67. A video farm or local area network ofvideo servers each having (a) deliverable video resource of a specifickind available for serving out, and (b) a resource manager adapted to(i) receive a demand indicator input indicative of demand for aparticular one of said deliverable video resources of said specific kindand (ii) derive a video resource-varying output adapted to varycapability of said video farm or local area network as a whole to serveout said particular one video resource.
 68. A video farm or local areanetwork comprising a plurality of video servers adapted to serve outvideo resources of a specific kind; a usage monitor; and a resourcemanager; said usage monitor being adapted to monitor usage of said videoresources and to determine if a usage level of a particular saidresource has changed significantly and to communicate such changes inusage level to said resource manager, said resource manager beingadapted to perform at least one of the following: (a) introduce anadditional video server to said farm or local area network, (b) start upa video resource serving application on a farm or networked video serverif usage of said video resources has increased significantly; (c) removesaid specific video resource from a farm server or local area networkedvideo server; or (d) shut down a video resource-serving application on afarm server or local area networked video server if said usage of saidvideo resource has decreased.
 69. A rich media content management serveradapted for use with a rich media content server farm or local areanetwork, said rich media content management server comprising a servablerich media content monitor adapted to monitor levels of usage ofservable rich media content of a specific kind, and a rich media contentavailability manager adapted to change the availability of specificservable rich media content depending upon demand for said specificservable rich media content; said rich media content management serverbeing adapted to perform at least one of the following (a) introduce anadditional rich media resource server to a network, (b) start up a richmedia content serving-application on a rich media content server iflevels of usage of a particular rich media content have increasedsignificantly, (c) remove rich media content from a networked rich mediacontent server and (d) shut down a rich media content servingapplication on a rich media content server if levels of usage of aparticular rich media content have decreased significantly.
 70. A memoryincluding software for controlling the distribution of video servingapplications over video servers of a video farm or network, the softwarecomprising a demand evaluation operative for establishing levels ofdemand for particular video serving applications available on said farmor network, and a resource allocation operative to receive input fromsaid demand evaluation operative and to cause: (i) video servingapplications to be copied from one video server of said farm or networkto another video server of said farm or network thereby to increasecapacity of said farm or network to serve out video files in aparticular format; or (ii) cause a specific video serving application tobe started up to enable a video file to be servable out from at leastone additional port address of a video server that already has a videoserving application so as to increase capacity of said video server toserve out a video file in a specific format; or (iii) cause anadditional video server, not previously part of said farm or network, tobe co-opted into said farm or network so as to increase capacity toserve out video serving applications; or (iv) cause any one of, orcombination of, (i), (ii) or (iii) to occur.
 71. A method of maintainingavailability of requested network resources in a network of servers eachhaving associated network-servable resources of a specific kind, themethod comprising dynamically distributing servable resources betweensaid resource servers dependent upon demand for said resources, therebyvarying capability of said network as a whole to serve out a particularresource dependent upon the level of demand for said particular resourceand wherein said resource servers have port addresses, and making aparticular resource servable from a first port address available forserving from a second port address associated with the same server assaid first port address.
 72. A method of maintaining availability ofrequested network resources in a network of servers each havingassociated network-servable resources of a specific kind, the methodcomprising dynamically distributing servable resources between saidresource servers dependent upon demand for said resources, therebyvarying capability of said network as a whole to serve out a particularresource dependent upon the level of demand for said particular resourceand wherein an additional resource server, not part of said network at afirst time, joins said network in order to increase capacity of saidnetwork to serve out said particular resource, and copying saidparticular resource to said additional resource server to enable saidadditional resource server to be capable of serving out said particularresource.
 73. A method of data storage management of data in a networkcomprising the steps of: (i) monitoring usage of a servable resource;(ii) determining if said usage of said resource has increased ordecreased; and performing at least one of steps (iiia) and (iiib), step(iiia) including starting up a resource-serving application on aresource server if said usage has increased; and step (iiib) includingshutting down a resource-serving application on a resource server ifsaid usage has decreased.
 74. A method of data management comprising thesteps of: (i) monitoring traffic on at least one data content server ofat least one of a network and software application response time for anapplication software running on at least one data content server on anetwork and (ii) starting up or shutting down an appropriate dataserving application automatically upon said server or upon a furtherserver on the network in response to at least one of network traffic andapplication response time, wherein step (ii) is executed in response toa change in network traffic due to any of the following: data servingapplication failure, data serving application response time, dataserving application overload of said server, insufficient servers havingsaid data serving application present upon a server network based upon astatistical model.
 75. A network of resource servers each havingdeliverable resource of a specific kind available for serving out, and aresource manager adapted to receive a demand indicator input indicativeof demand for a particular one of said deliverable resources of saidspecific kind and to output a resource-varying output adapted to varycapability of said network as a whole to serve out said particular oneresource, and wherein said resource-varying output comprises a source ofresource migration signal for causing said particular one resource tomigrate from one resource server to another server.
 76. A network ofresource servers each having deliverable resource of a specific kindavailable for serving out, and a resource manager adapted to receive ademand indicator input indicative of demand for a particular one of saiddeliverable resources of said specific kind and to output aresource-varying output adapted to vary capability of said network as awhole to serve out said particular one resource, and wherein saidresource-varying output comprises a source of resource migration signalfor causing said particular one resource to migrate from one resourceserver to another server, and wherein said resource servers have portaddresses and wherein said particular one resource is available forserving from one port address of a said server and wherein said resourcevarying output is arranged for causing either (i) a second port addressof the same said server particular resource available for serving; or(ii) a reduction in serving capacity of said network as a whole to serveout said particular resource by reducing the port addresses of one ofsaid server operating to serve out said selected resource down from aplurality of port addresses to a smaller number of port addresses ofthat said server.
 77. A network including a plurality of the videoservers of claim
 48. 78. A network including a plurality of the videoservers of claim
 49. 79. A network including a plurality of the videoservers of claim
 52. 80. A network including a plurality of the videoservers of claim 53.